Why 24-bit
From Benchmark
Why do I need a 24-bit USB audio device to play 16-bit 44.1 kHz music files?
The reason is that digital volume controls and digital mixers increase the word-length of the audio. The longer word-length is a result of multiplication and addition. These arithmetic operations produce long word-lengths that must be squeezed back into a shorter word length. Word-length reduction adds noise and/or distortion to the audio. The amount that is added is determined by the output word length.
The noise and/or distortion added by word-length reduction decreases by 6.02 dB for every additional bit that can be retained. Reduction to 16-bits adds 48 dB more noise than reduction to 24-bits. In general, 16-bit word-length reduction is very audible; while 24-bit word-length reduction produces noise levels that are well below audibility.
Our tests show that 24-bit output devices deliver a dramatic improvement in sound quality even when playing 16-bit material. Native USB output devices have had a reputation for poor sound quality. This is primarily due to the 16-bit limitation.
Benchmark's Advanced USB Audio technology breaks the 16-bit barrier and delivers pristine digital audio to the D/A converter. Benchmark's UltraLock™ system insures that the D/A converter delivers this audio to the analog outputs without adding jitter-induced distortion artifacts
