Is no preamp the best preamp of all?

08-26-11: Daverz
What does 75-85% translate to in terms of dB?

I'm aware that I'm losing information when I use digital attenuation, but how does this translate into what one hears that is different that what one hears when an analog volume is lowered. Saying that one "loses resolution" is not really telling me anything as I don't know how a "loss of resolution" sounds different from just a lower volume.

it is not meaningful to just cite a figure like "75%-85% because you need more information. as a general matter, each 6dB reduction corresponds to a 1/2 reduction in power (or 3dB reduction in voltage). this means that you are losing 1 bit of resolution for each 6dB. redbook cd stores audio with 16 bits of resolution/channel (but the actual resolution, as a practical matter, is more like 14 bits). so what you need to know is how many bits of resolution is used by the audio processor in your cd player. i have a wadia 381, which operates with 21 or 22 bits of resolution. each step in the wadia digital volume control reduces the (power) output by 1 dB. so, i can reduce the digital volume to around 65% to 75% before i start to face the potential of losing significant bits of audio information.

my personal belief is that these are the considerations for deciding whether to go through a pre-amplifier or direct:

1)some people like the way that the pre-amplifier colors the sound from the cd player. such people should go through the pre-amplifier instead of going direct;

2)when i want to listen a low volume levels (like late at night), i tend to go through the preamplifier. this gives you a lot of latitude in how you manage volume: there can be drawbacks to turning the volume level too low on a pre-amplifier, so you set the volume level on the pre-amplifier to be in the range you desire and then adjust the digital volume to bring the volume the rest of the way down;

3)there are some recording (like some classical recordings) where the recording level is much lower than that of many popular recordings. in such cases, you would need to go through the pre-amplifier to get sufficient gain to achieve the volume level that you desire.

09-05-11: Amfibius
There is no such thing as no preamp. A preamp is simply gain stage + volume control. Just because your DAC has a built-in gain stage and volume control, and you elect to connect it directly to your power amp, does not mean that you do not have a preamp in the circuit. You do - your preamp is built in to your DAC. If your DAC has an elaborate gain stage, then adding a preamp would quite concievably worsen the sound, because you would be adding additional circuitry.

you're thinking about *analog* volume control; digital volume control works differently (i'm not going to go through the detail of digital volume control here because it has been discussed many times before) and does not have the issue to which you are referring. as a clue, if you see a device that has fixed and variable outputs, then the volume control being implemented is most likely analog. with a digital volume control system, you would typically only have a single output (of course you might actually have both single ended and balanced outputs, but they would be carrying the same signal).