I'm using a Pure i20 dock for iPod right now, which includes a DAC and thus volume control. I was wondering about the same thing at the time, in one of the threads:
- the general idea is that there should be no signal degradation since it's digital (i.e. bit-shifting up or down) unless you hit the limit and things start to clip...
- but somebody on there contacted Pure and the technical reply was that basically max. volume equals standard full digital output, i.e. same as straight out (and max. volume/voltage on the line out). Only when you turn the volume down will it start altering the digital signal, and since it's downwards there's no chance of clipping.
I figure other DACs with digital volume will work the same, and there should be no -noticeable- signal degradation. But I'm sure there will be always those who claim to hear such a thing. Personally I never could, and having recently acquired a straight transport (with no DAC and thus volume control), frankly the missing convenience has a much larger impact than any imperceptible "degradation".
