PigletsDad said:The downside of this approach is that you reduce DAC resolution at anything other than full volume. To take any extreme example, say you want or need to listen at -90dB. This corresponds to losing 15bits of resolution. On a 16bit sound card, you are down to 1 bit conversion, and even a 24bit one only has 9bits active. Of course, this should be very quite, so may be it is not a problem.
At the very least, I would want to set the gains pretty carefully, so that full gain corresponds to the loudest you want to listen, and so the amount of resolution loss at normal levels is minimised.