Astell&Kern A&ultima SP4000T DAP Review: The World's First Quad Tube DAP to Rewrite the Rules
Read Time: Approx. 16 min.
TL;DR:
- The SP4000T is Astell&Kern's most advanced DAP to date, featuring a first-of-its-kind quad vacuum tube configuration alongside solid-state amplification
- Three distinct tube modes — Triode, Ultra Linear, and Pentode — plus Hybrid and OP AMP modes give listeners 54 unique ways to shape their sound
- A flagship HEXA DAC architecture (dual AK4191EQ + dual AK4499EX chips) ensures clean, high-resolution digital-to-analog conversion untouched by digital noise
- Full Android 15 support with an open Google Play Store makes it as practical as it is audiophile-grade
- At $3,620, it's a premium investment, but one that effectively delivers two DAPs in one — analog warmth and solid-state precision
The Quad Tube DAP That Changes Everything
Just when you think the DAP Mongol Astell&Kern has pulled the last rabbit out of its hat, they continue their evolution of tube excellence with the release of the A&ultima SP4000T Digital Audio Player. As the company's third DAP to feature real vacuum tubes alongside solid-state amplification technology inside the same chassis, the SP4000T pushes the boundaries of what's technically possible in portable audio.
At $3,620, the SP4000T is the culmination of two years of dedication and exploration, taking what's been learned from the A&ultima SP4000 DAP and the SP3000T and channeling it into a single defining question: How can we bring deeper emotion through analog sound? The answer is everything you see–and hear–in this player. With support for the full Android OS, including the Google Play Store, 54 ways to shape your sound, a flagship-level DAC chipset, AK file drop support, and Astell&Kern's signature striking design, the SP4000T invites audiophiles in as the ultimate flagship digital audio player and hi-fi companion.
PROS
- Unmatched versatility with 3 Tube Amp Modes, OP AMP Mode, and Hybrid Mode
- Full Android OS with no restrictions, 10-hour battery life, and works with AK docking cradle
- Astell&Kern signature sound mixed with the analog warmth of tubes
CONS
- Weight combined with a large form factor makes it a tad bulky; not a one-handed device
How does the SP4000T DAP differ from the SP3000T DAP?
Unlike the SP3000T, the SP4000T is equipped with four RAYTHEON JAN6418 tubes, further enhancing its analog sound characteristics. By applying the Triple AMP system, the SP4000T perfectly harmonizes the true analog sound of Quad vacuum tubes with the dynamic sound of an OPAMP in a single chassis.
It also builds on what was learned from the A&ultima SP4000 and the SP3000M, advancing the platform's processing power, noise architecture, and connectivity in meaningful ways.
Design
With each new release, it seems Astell&Kern's DAPs get slightly larger and larger–except for the pocket-sized SP3000M. More tech requiring more space? Bigger is always better? Whatever the methodology is behind the dimensions, the SP4000T is ever-so-slightly larger than the SP4000 DAP, by literally a few tenths of an inch, give or take.
As for controls, Astell&Kern keeps it simple. On the top panel, you'll find two headphone jacks–a single-ended 3.5mm headphone output and a 4.4mm balanced headphone output–and a lock/unlock switch. The volume wheel on the right side doubles as the power button, turning on and off when held down, and the left side features all your basic control buttons: Triple mode menu, track skipping, and track play/pause. The bottom panel features a USB-C port for charging and connection to external devices, and a slot for one microSD card.
With 256GB of internal storage and support for a 1.5TB micro SD card, there's ample room for your carefully curated personal music library. When it comes to streaming, the SP4000T supports the top audio formats and sample rates up to DSD512 and PCM 768kHz. Wi-Fi 802.11 is supported and Bluetooth 5.2 with the top codecs available (A2DP, AVRCP, Qualcomm aptX HD, LDAC, LHDC, SBC, AAC). BT Sink mode is also supported, which is a welcome addition for listeners who want to route audio from a phone or tablet wirelessly.
Enjoy approximately 10 hours of playback on a single charge. Obviously, the more you run on it, the quicker the battery will drain, but I was able to get a full workday of listening in, bouncing between the tube modes and running the SP4000T through its paces. The unit's 7,450mAh 3.8V Li-Polymer battery takes roughly 5 hours to reach a full charge courtesy of the PD 3.0 fast charging feature.
The SP4000T includes an enhanced battery protection mode that limits how fully the battery charges. Since continuously charging to 100% can shorten its lifespan, this feature allows you to set a maximum charge level between 80% and 95% directly in the settings.
Currently, the SP4000T is available in a striking silver finish with a unique blend of matte and mirror accents on the back. The matte finish is definitely a fingerprint magnet, but that's expected of anything matte. The SP4000T sports the same large display screen as the PD20 DAP, at a whopping 6-inch full HD. Astell&Kern DAPs have one of the best user experiences of any Digital Audio Players on the market, and with a Full Android OS, the SP4000T is a dream to use. The options are virtually endless. Add any app (that's supported) from the Google Play Store, whether that's your favorite TV streaming service, podcast app, or the place you get the news–the SP4000T is versatile for daily use.
Included with the SP4000T is a USB-C to C Cable and leather case, composed of MINERVA leather from BADALASSI CARLO, a renowned leather workshop located in the San Miniato district of Florence, Italy. The warm, cognac color of the case snugs the SP4000T perfectly, providing a secure fit while featuring a rear pattern cut out that showcases the tube LED glow. The SP4000T is compatible with Astell&Kern's docking cradle, first introduced with the PD10 DAP. This is a great aftermarket accessory for anyone looking to use the DAP at home in a speaker system setup.
Sound
The SP3000T Digital Audio Player was the first Astell&Kern DAP I heard with built-in vacuum tubes. Up to this point, I was familiar with the tube sound, and as a warm and musical lover, I was hooked on that analog warmth. So the thought of having that in a portable form factor was a dream come true. The SP4000T continues that dream, and I couldn't be more thrilled.
But the SP4000T isn't just a vacuum tube DAP. It also supports playback through solid-state amplification. So to provide the most accurate listening impressions, I've tested both and detailed my experience using IEMs and over-ear headphones.
The Star of the Show: Real Vacuum Tubes
To fully appreciate the three-tube modes in the SP4000T, we've got to do a quick crash course on how it all works. The SP4000T uses four RAYTHEON JAN6418 Vacuum Tubes to make up its tube amplification circuit. Each of these tubes is precisely measured, perfectly positioned, and working together in perfect balance to deliver rich harmonics. To emulate a true analog sound experience, Astell&Kern integrated its Triple Amp Mode, which uses three modes–Triode, Ultra Linear, and Pentode–to encompass the full expressive range of a tube amplifier.
Triode Mode brings out rich harmonics and texture in a track for an overall sound quality that's warm and lush.
Pentode Mode retains the signature warmth of a vacuum tube while stripping away reverb, delivering a clean, powerful presentation that speaks with directness and force.
Ultra Linear Mode is the happy middle, blending the tonal color of Triode Mode with the output of Pentode Mode. The sound fades softly as it edges, yet carries a firm, solid core. It's balanced and smooth.
When selecting the tube mode, there are also three tube current modes to choose from: high, mid, and low. Low for Triode mode, mid for Ultra Linear Mode, and High for Pentode mode. They don't explicitly state which current to use for each mode, but with some context clues on the product page, I was able to figure it out. Starting with the 64 Audio U12t Universal IEMs, I switched between the three modes, listening intently to Oliver Tree's track "1993", Ariana Grande's new track "Hate That I Made You Love Me", and Olivia Rodrigo's new album You Seem Pretty Sad for a Girl so In Love. Here are my impressions:
In Triode Mode, the presentation becomes noticeably more resolved, especially across several of Olivia Rodrigo's slower, more emotional tracks. When listening to Oliver Tree's grungy sound, the low-end and midrange were impactful yet controlled with a punch that never felt overbearing. This was my preferred mode for pop and some of the coffeehouse tracks in my library. It picked up the subtle background details in Ariana Grande's track that are easy to miss. There's a particular element–what I can best describe as a bubbly, high-pitched synth–that sits behind the main melody. It's something I've heard faintly in my car, but through the Campfire Audio Chimera Universal IEMs, it practically jumped forward in the mix.
In Pentode Mode, the sound shifts to something much more bold and authoritative than Triode Mode. This is the mode I would reach for when listening to rock and metal genres–anything with a lot of energy, grit, and impact. On "1993," it delivers the most industrial-leaning presentation, emphasizing the track's gritty, textured backend with impressive precision. Everything I threw at it came across clean and powerful with immediacy. However, with Grande's track, some of that airy, ethereal quality of her voice was reduced, so this wouldn't be my mode of choice for ballads. It's not a drawback. You're just trading some of that lush, atmospheric character for a more direct and grounded presentation, and that's where Ultra Linear Mode comes in as the happy middle.
Ultra Linear Mode blends the sonic strengths of Triode and Pentode modes, delivering a smooth, yet firm and prominent presentation. Elements like the electric guitar in one of Rodrigo's tracks come through with a strong presence. This is the happy middle of all three modes.
Now, in hybrid mode, you still get access to the three tube modes and tube currents while reaping the benefit of solid-state amplification. It's a unique mode that gives you the best of both worlds. I found myself settling into hybrid mode after I tested the tube modes and OP AMP stage. It was the perfect middle ground that added warmth with technical precision.
OP AMP Precision
OP AMP mode showcases the precision and accuracy that Astell&Kern DAPs are known for. The AKM flagship DAC chipset really shines here, delivering a clean, highly detailed, and organic sound. AKM DAC chips are known for this, and they're one of AK's favorite chipsets to use, so I wasn't surprised when the SP4000T delivered that signature sound.
Olivia Rodrigo's new album is a nice blend of pop hits and emotional ballads, featuring piano, electric guitar, and expressive vocals. The SP4000T's OP AMP mode handled the quick pace of her tracks with ease without letting any fine details slip through the cracks. Listening with the Focal Utopia 2022 Headphones and our Blue Dragon Premium Headphone Cable, I enjoyed an airy, organic presentation where each piano key and breathy lyric of Olivia Dean's song "So Easy (To Fall In Love)" was rendered effortlessly. The Utopia 2022 required me to turn the volume up more than I did with the IEMs I tested, but the SP4000T handled the demand as if it was nothing.
Who is the Astell&Kern A&ultima SP4000T DAP for?
So here's the thing about these three tube modes: I can't choose my favorite, nor say which is better than the other. They each have their rightful purpose, and that depends on what you're listening to, what mood you're in, and what you're trying to achieve. I'm the first person to label myself a music enthusiast over an audiophile any day. I listen to music to escape. To get lost in a world outside of my own, so I rarely listen intently.
My personal library bounces between pop, alternative, EDM, hip-hop, and everything in between. I tend to listen to pop and hip-hop the most, but depending on the vibe, it might be a reggae or country kind of day. Truly, there is no rhyme or reason to my music collection, and because of that, I haven't found that perfect piece of gear that works with everything I listen to. I feel like Goldilocks, wondering when my perfect bowl of porridge will come along. Little did I know, Astell&Kern, the company known for making the impossible possible, had been busy conjuring up the solution to my 21st-century dilemma.
The SP4000T caters to my evolving library and ever-changing listening habits, and I think that's the beauty of this device. The true selling point here isn't the fact that it's the first DAP to use four vacuum tubes and harness the power of Android 15. It's that it offers something for everyone. Every type of listener is taken care of.
The analytical, detail-oriented audiophile seeking the precision of solid-state amplification can enjoy the nuance of their favorite tracks. Tube enthusiasts desperately seeking a way to enjoy that warmth on the go can. While this isn't Astell&Kern's first attempt at a DAP with vacuum tubes in it, it's the model that perfects it, going above and beyond to deliver you the best of both worlds: analog warmth and technical precision. You're in the driver's seat of your listening experience with 54 possible combinations tailored to every genre you enjoy.
Stupid Song
By Olivia Rodrigo
(You Seem Pretty Sad for a Girl so in Love)
Nice to Each Other
By Olivia Dean
(The Art of Loving)
1993 (feat. Little Ricky ZR3)
By Oliver Tree
(Ugly Is Beautiful)
Hate That I Made You Love Me
By Ariana Grande
(Petal)
Features
- Industry-first DAP with MIL-Spec Vintage Vacuum Tube Raytheon JAN6418 in Quad Configuration
- Industry-first DAP with Triple Tube Mode (Triode, Ultra Linear, Pentode)
- T Series Signature feature: Triple AMP System
- Adjustable Tube Current with Three Levels
- High Driving Mode, ESA, and Advanced DAR for superior sound quality
- Full Open Android
- Enhanced Octa-Core CPU
Digital Architecture: Flagship AKM DAC Chipset
At the heart of the SP4000T sits a high-end discrete HEXA circuit architecture. Two AK4191EQ digital modulators handle the digital noise reduction, completely separated from the two flagship AK4499EX DAC chips that handle the analog conversion. This quad-dac configuration is part of what earns the SP4000T its HEXA designation, and it's the same approach used in Astell&Kern's top-of-the-line solid-state siblings.
This physical separation ensures high-frequency digital switching noise never contaminates your sensitive analog tube sound. This is an infamous DAC chipset used by Astell&Kern in several of their DAPs, including the SP4000. 7 DAC filters are available for you to fine-tune the sound how you like, be it natural with a super slow roll off or acoustic with a sharp edge and post echo to enhance bass.
Quad Vacuum Tubes & Triple Tube Mode
Before you start jumping to conclusions, no, the SP4000T is not just another release of the SP3000T with a new name. It's completely different. Where the SP3000T had only two vacuum tubes, the SP4000T has four–and that difference is anything but subtle. Incorporating real vacuum tubes into a device as small as a DAP is not an easy task, and for Astell&Kern to have squeezed four into a single chassis is beyond impressive. Here's exactly how they did it:
Four MIL-Spec vintage RAYTHEON JAN6418 vacuum tubes sit in a quad configuration, making the SP4000T the first DAP in the industry to feature this. Each of these tubes is divided into a fully balanced, channel-separated dual structure, with each pair of tubes mirrored for both the left and right channels working in a differential configuration. This enables the SP4000T to cancel out common-mode electrical noise and deliver incredibly clear voltage amplification.
Because of this quad-tube setup, Astell&Kern introduced Triple Tube Mode–triode mode, pentode mode, and ultra linear mode–giving you full control over how these tubes operate. Triode mode maximizes rich, even-order harmonics, bringing a lush decay and organic warmth to the sound quality that makes acoustic instruments and vocals sound incredibly lifelike. Pentode mode shifts the focus to maximum output and dynamic impact, delivering a tighter, more energetic presence that hits hard. Finally, ultra linear mode sits right in the middle, blending the tonal richness of triode mode with the firm control of pentode mode.
Triple AMP System: The Perfect Harmony of Real Vacuum Tubes and OPAMP
The SP4000T isn't limited to just vacuum tube enthusiasts. Audiophiles seeking the technical precision associated with solid-state amplification are catered to with three amplification modes available: solid-state OP AMP mode, tube amp mode, and Hybrid amp mode. Tube amp is, well, tubes. That's where you'll get the pure vintage warmth only a real vacuum tube can deliver. AK's triple amp mode was first introduced in 2021 with the A&ultima SP2000T, continued in the SP3000T, and perfected in the SP4000T.
OP AMP mode uses pure, solid-state amplification to deliver you maximum clarity and an expansive soundstage. Hybrid mode offers five adjustable levels, allowing you to blend the precise resolution of the solid-state amp with the muscality and warmth of the tubes to match your exact preferences. It's subtle inclusions like these that make the SP4000T such a versatile device. You're essentially getting two DAPs in one. In the mood for subtle analog warmth to complement those vintage tracks? No problem, just flip on tube amp mode. Diving into some critical listening that requires absolute precision and detail? Switch over to OP AMP mode. It's that simple.
But perhaps the biggest upgrade over the SP3000T is the sheer amplification power. The SP4000T inherits the High Driving Mode from its solid-state sibling, the SP4000 DAP, which matters for those planning to use OP AMP mode. High Driving Mode provides powerful and stable output, reproducing even the most delicate sonic details with precision for a deeper, clearer, and more immersive listening experience.
And those operational amplifiers aren't just thrown in; they're purposefully arranged in a parallel configuration horizontally, rather than linearly. Unlike OPAMP series configurations that increase noise while boosting power, the SP4000T's parallel alignment expands the driving range horizontally with no noise increase or SNR reduction. This means you get a massive 8.0 Vrms of output in balanced mode without introducing background hiss or distortion. So whether you're using highly sensitive IEMs or notoriously demanding planar magnetic headphones, the SP4000T has the current to drive them flawlessly.
2nd Generation Anti-Microphonic Noise Architecture
You've probably seen dedicated tube headphone amplifiers with metal cages, glass partitions, and other physical barriers to isolate and protect from the rest of the gear. Personally, I figured that was because they get extremely hot, but Astell&Kern explains there's more to the science than this. Vacuum tubes are delicate by nature and incredibly sensitive to physical impact. Even a light tap can cause the glass filaments to ring, creating an annoying echo known as microphonics. To combat this, Astell&Kern incorporated its five-stage Anti-Microphonic architecture, the second generation of the technology first used in the SP3000T.
The tubes are mounted on a flexible, independent Any layer HDI PCB completely isolated from the main board, wrapped the tube leads in custom silicone, suspended the tubes mid-air with silicone dampers, and then covered the entire assembly in a 99.9% pure copper shield can to block electromagnetic interference.
Additional Features, Filtering, and UI
To further refine the sound, Astell&Kern includes Enhanced Signal Alignment (ESA) technology to minimize phase distortion and Advanced Digital Audio Remaster (DAR) technology–along with Astell&Kern Direct Path (ADP), a signal routing mode that bypasses all processing stages and sends the audio signal straight to the output in the most transparent configuration possible for true bit-perfect playback. While this upsampling technology may feel insignificant compared to the grandeur of the vacuum tubes, DAC architecture, and OP AMP configuration, it serves a vital purpose in delivering you an exceptional listening experience. ReplayGain is also supported alongside crossfeed.
Many hi-fi manufacturers will include extra technology and features just to raise the price by a few hundred dollars and slap on a "flagship" title to the product name. But Astell&Kern is not one of those companies. They're intentional and driven by the user experience. They want to deliver you a top-of-the-line product that rivals dedicated desktop units, and they do so successfully with every new release.
ESA is incorporated into the SP4000T with a single purpose: to improve Group Delay–one of audio's most persistent challenges. ESA aligns frequency signals so they arrive more uniformly, minimizing frequency distortion and delivering sound with greater clarity and purity. Advanced DAR delivers an even more natural and refined sound. Rather than passing the audio signal directly to the DAR engine, it first routes through VSE (Virtual Sound Extender) to restore lost harmonics and enhance audio quality, then applies DAR technology in a second stage for a more complete upsampling result. This allows you to enjoy a deeper, more immersive sound that's closer to the original recording.
As mentioned earlier, the SP4000T runs on an open Android 15 platform with full Google Play Store support. This means no more app whitelists. You can now download Tidal, Qobuz, Spotify, Apple Music, or whatever you prefer directly to the device. And that capability expands beyond music streaming service apps. It's also Roon Ready for the Roon users. You can download virtually any app on the Play Store that's supported on the SP4000T. While you could technically play Candy Crush or rip through crossword puzzles, you always want to be mindful of the DAP's performance load. Just because you can doesn't always mean you should.
Dragon Cables
Why Dragon Cables? You’ve heard the saying that a chain is only as strong as its weakest link, right? Well, the same applies to your brand-new audiophile-grade headphone or other audio components. The weakest link, in this case, is your stock cable or the cheap interconnects the manufacturer threw in the box just to get you up and running. Why is the cable always an afterthought, when it’s just as important as the rest of your system? At Moon Audio, we use the best raw materials in our cables to unveil your music. We believe the materials matter and your audio cables should have the same care and craftsmanship that manufacturers put into their audio components and headphones. Audio cables are ultimately the connection to your music. The fact remains that cabling is often considered the last priority to that of the main product and a means to cut down the overall production costs. It’s as simple as that.
Verdict
To answer the question on everyone's mind: is the SP4000T a true upgrade from the Astell&Kern A&ultima SP3000T DAP, or just a refresh with a new name? The SP3000T was a landmark product–AK's first dual-tube DAP and proof that vacuum tube amplification could work in a portable form factor. It delivered warmth and musicality that turned heads and won over skeptics. But the SP4000T takes that foundation and rebuilds it, improving on every aspect of the SP3000T. The jump from two tubes to four, three-tube modes, second-generation anti-microphonic architecture, and the upgraded HEXA DAC layout are just a few of the SP4000T's noteworthy qualities.
If you're coming from the SP3000T, these upgrades might feel incremental, but the addition of the full Android OS is an enticing incentive. If the SP3000T convinced you that portable tube audio was worth pursuing, the SP4000T is the device that perfects it.
At $3,620, the A&ultima SP4000T DAP sits at the top of AK's lineup as the company's new flagship. This is a player that treats the vacuum tube not as a cosmetic addition but as the centerpiece of an expertly constructed engineering system. The quad tube configuration, 54-combination sound palette, next-generation noise suppression, and HEXA DAC architecture put the SP4000T in a class of its own.
But beyond the specs and engineering achievements, what makes the SP4000T truly special is how effortlessly it adapts to the listener rather than demanding that the listener adapt to it. Whether you're deep into critical listening sessions or simply unwinding with a playlist that jumps between hip-hop, jazz, and acoustic, there's a mode built for that moment. The SP4000T isn't just a statement piece. It's the DAP that grows with you as your music tastes evolve. If you're connecting the SP4000T to a desktop DAC or your computer via USB-C, the Silver Dragon USB Cable is a natural companion that honors the engineering investment you've already made in the device itself. If you have questions or want help pairing it with the right Dragon Audio Cables or IEMs, reach out to us–we're happy to help you build the perfect system around it.
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What's in the Box
- Astell&Kern A&ultima SP4000T DAP
- Premium leather Cognac-colored case
- USB-C to C Cable
Specifications
GENERAL SPECIFICATIONS
Model: SP4000T (PPF52)
Body Color: Silver, Copper
Body Material: Stainless Steel, Copper
Display: 6-inch 2K (2160 x 1080) touch screen
Dimensions: 3.37" W x 5.9" H x 0.76" D (85.7mm W x 150mm H x 19.5mm D)
Weight: About 19.9 oz (565g)
Input: USB Type-C input (for charging & PC & MAC)
Outputs: Unbalanced Out (3.5mm), Optical Out (3.5mm), Balanced Out (4.4mm, only 5-pole supported)
Wi-Fi: 802.11 a/b/g/n/ac/ax (2.4/5GHz)
Bluetooth: V5.2 (A2DP, AVRCP, Qualcomm aptX HD, LDAC, LHDC, SBC, AAC)
Feature Enhancements: Firmware upgrade supported (OTA)
Operating Temperature: 0℃ ~ + 40℃ (32℉~ 104℉)
Built-in Memory: 256GB [NAND]
External Memory: microSD x1 (Max 1.5TB)
Battery Capacity: 7,450mAh 3.8V Li-Polymer
Charge Time: About 5 hours (PD3.0 charging)
Playback Time: About 10 hours (Standard: FLAC, 16bit, 44.1kHz, Vol.80, LCD Off, Low Gain)
Supported OS: Windows 10, 11 (32/64bit) MAC OS X 10.7
CLOCK SOURCE
Clock Jitter: 25pS (Typ)
Reference Clock Jitter: 200 Femto Seconds
AUDIO SPECIFICATIONS
Supported Audio Formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF
Sample Rate:
PCM : 8kHz ~ 768kHz (8/16/24/32bits per Sample)
DSD Native: DSD64(1bit 2.8MHz), Stereo / DSD128(1bit 5.6MHz), Stereo
DSD256(1bit 11.2MHz), Stereo / DSD512(1bit 22.4MHz), Stereo
Output Level: Unbalanced 4.2Vrms | Balanced 8Vrms (Condition No Load)
CPU: OCTA-Core
DAC: AKM4191EQ x2 + AKM4499EX x2
Vacuum Tube: RAYTHEON JAN6418 x4 (Quad Tube)
Decoding: Support up to 32bit / 768kHz Bit to Bit playack
Frequency Response:
±0.006dB (Condition : 20Hz~20kHz) Unbalanced │ ±0.006dB (Condition : 20Hz~20kHz) Balanced
±0.06dB (Condition : 20Hz~70kHz) Unbalanced │ ±0.06dB (Condition : 20Hz~70kHz) Balanced
S/N: 124dB at 1kHz, Unbalanced | 125dB at 1kHz, Balanced
Crosstalk: -136dB at 1kHz, Unbalanced | -145dB at 1kHz, Balanced
THD+N: 0.0006% at 1kHz, Unbalanced | 0.0004% at 1kHz, Balanced
IMD SMPTE: 0.0004% 800Hz 10kHz (4:1) Unbalanced | Balanced
Output Impedance: Unbalanced Out 3.5mm (0.7 ohms) | Balanced Out 4.4mm (1.7 ohm)
