In the 11/1998 Stereophile, B. Damkroger noted the following about the CL-15's (Calif. Audio Labs CD player) digital volume control:
Volume control is implemented in the digital domain, so it doesn't change the analog gain but rather the digital-to-analog scaling. According to CAL, reducing the volume won't result in a loss of resolution as long as the CL-15 is operated in the top two-thirds of its output range, with less than 18dB of attenuation.
I assume by "resolution", one means bit depth. In any case, if the volume is truly controlled ONLY in the DIGITAL domain, can anyone (JA?) comment on why CAL may have made that comment?
On a more general note, at what volume scales -- for either analog or digital volume controls -- is audio quality "better"? E.g., two o'clock -> 100% on tradit. analog rotary volume knobs (this seems to work best for me on preamps, tho' often I can't use preamp vol. levels that high because the source volume/gain is high and non-adjustable) .
There could be multiple (concurrent) reasons for the above including:
-- better impedance matching between volume control and the stage following it, etc.
-- less (noisy) resistive material for signal to pass thru (for tradit. analog pots)