Current Mode Amplification (CMA)
CMA is the patented design used in Questyles flagship CMA800R headphone amp. Current mode amplification uses transistors to amplify. While the core amplification takes place in the current domain in pure Class A, the output stage can be changed to either class A or AB. The structure of the CMA amplification circuit is completely different from the traditional voltage mode amplifier.
The capacitance between the transistors, which affect the speed and bandwith, operate at a very low impedance. The full power bandwith of the entire amplifier loop is very similar to the bandwith of a closed loop. The SR grows linear with input signals and a strong, speed negative feedback loop. These features not only eliminate the TIMD, but also achieve amplification with a wide bandwith and ultra-low distortion.
Affordable featured all-in-one device
The Questyle Audio CMA600i headphone amplifier section follows Questyle’s patented "Current Mode Amplification" design used in their flagship headphone amplifier, the Questyle Audio CMA800R.
The CMA600i has impressively low 0.00034% distortion, with up to 950mW on tap, for low impedance headphones. The CMA600i can also handle heavy loads with a 4-pin balanced XLR connection to maximize sound quality.
The entry level CMA600i utilizes a USB port that adopts a unique 3X Clock structure. This ensures a proper sync with the premium AK4490 32-bit DAC chipset from AKM.
The chipset includes a newly developed switch capacitor filter "OSR Doubler" that greatly reduces sound degradation from noise shaping, achieving a flat noise floor up to 200kHz! The AK4490 chip obtains first class sound performance by also reducing jitter and pre-ringing to undetectable levels.
Premium DAC section with True DSD
Unlike other DACs that claim DSD support, yet in actuality provide DoP (DSD over PCM), the Questyle Audio CMA600i accepts the DSD bit-stream directly from your computer, bypassing your computer’s audio processing and digital volume control as well as the Questyle Audio CMA600i’s digital filters, to provide True DSD, the way it was meant to be heard.
Supports highest quality formats
The Questyle CMA600i is designed to grow with your music collection. As well as supporting standard digital files via USB, toslink or coaxial SPDIF connection the CMA600i is also fully compliant with files up to DSD256 and PCM 384k/32bit over USB.
Separate pre-amplifier section
The Pre-Amplifier output is another shared feature of the Questyle Audio CMA800i and CMA600i.
Many manufacturers, when designing an all-in-one model, use the headphone amplifier circuit loop to support the pre-amplifier output to reduce costs.
To achieve the best possible sound performance, the Questyle Audio CMA600i is designed with a totally independent pre-amplifier.
10mm Thick Aluminium cover and bottom chassis
The Questyle Audio CMA600i’s aluminum chassis is produced by Foxconn, using precise CNC tooling machines. The upper cover and bottom chassis “mutual bit” structural design, provides the Questyle Audio CMA600i with stable heat, excellent control of sympathetic vibration and excellent shielding from RFI/EMI radiation.