D/A – Digital to Analog – A shorthand way to show the digital to analog conversion path.
DAC – Digital to Analog Converter – A device that converts digital data into an analog signal. Today, most audio is stored as digital data. So before being able to be heard through speakers, the DACs job is to convert this data into an analog signal which is then amplified to a speaker or headphone output. DACs are found in most of today’s electronics, but standalone or external DACs are usually far more superior than their internal factory counterparts.
DAP – Digital Audio Player – Simply put, a device that can play digital files. Higher-end DAPs include built-in, high quality digital to analog converters and headphone amps that can drive even power-hungry, high-end headphones. Not to be confused with an iPod or other standard MP3 playback devices (in this context), high fidelity DAPs can also play high-resolution format files like WAV and FLAC.
Dark/Darkness – Usually described when the higher frequencies are less prominent.
Decay – Describing the fade effect/length of a sound or note.
Decibel (dB) – A measure of the magnitude of sound, or more simply, how loud something is.
Depth – Describing how far away the instruments spacing is from back to front.
Detail – The subtlest, most delicate parts of the original sound, which are usually the first things lost my imperfect components.
Digital (Audio) – Sound that has been recorded in or converted to digital data. In digital audio, the signal has been encoded as numerical samples in a continuous sequence. In a CD, samples are taken 44,100 times per second, each with 16-bit sample depth.
Driver – The speaker within a headphone or earphone. There are many varying sizes, qualities and types.
DSD – Direct Stream Digital – A trademark used by Sony and Philips for their system of digitally recreating audible signals for the Super Audio CD (SACD). The DSD coding system differs than that of its competitor: PCM. A DSD recorder uses delta-sigma modulation.
DSP – Digital Signal Processing – As audio signals may be represented in either digital or analog format, processing may occur in either domain. Analog processors operate directly on the electrical signal, while digital processors operate mathematically on the digital representation of that signal. A digital representation expresses the audio waveform as a sequence of symbols, usually binary numbers. This permits signal processing using digital circuits such as digital signal processors, microprocessors and general-purpose computers.
Dynamic Driver – The most common driver type. Dynamic drivers are designed to be able to cover most of the spectrum of audible sound. Because of this, they are typically large and less detailed than their more expensive counterparts, balanced-armature drivers.