[adamlr]

I was wondering where you guys (i wonder if the guys i used to talk to are still here after all this time) turned the volume down from.
I for example, have a chain as follows: laptop - Odac - O2 - headphones.
I turn the amp up to 1 Oclock, the laptop at around 50%, and i use foobar as the main volume.
At work, we use professional sound equipment for large sound-systems and i know the common logic there is to always have the amps at full, preferring to lower the volume digitally. When I inquired, the explanation i got was that the amps loose "quality", or information when they turn down, whereas digitally, you still receive the full "resolution" of the sound, just more quietly. Somehow this doesnt sit right with my logic, i dont know why..

So i thought id ask the pros what do you say?

 

[castleofargh]

it's all a matter of getting the best out of what you got. typical audiophiles will tremble at the mention of not using 100% digital volume and lose "bit perfect" signal, but that sometimes works only in their head and the amp and headphone tent to be the main sources of fidelity loss anyway.

if your amplifier keeps a good dynamic and really low noise floor even when turning the knob down, then you can use that, no arm no foul.
with the same idea, if you're set at 24bit on your odac, you're not going to do much damage losing the lower 20 or 30dB to get your preferred listening level digitally. if you end up attenuating -100dB, obviously adjusting the amp makes more sense.
another possibility, if the amp has a significant and fairly fixed noise floor, any attenuation on the amp will bring the noise floor a little closer to the music. how close is the important question. on the other hand, if at max volume on the amp you start getting serious distortions into your load, it might be a good idea to dial down to a level where the distos are lower. so the optimal result might need a little trial and error with some measurements. if you really care, because in practice most setting will probably sound pretty fine.

personally, on my O2 I'm set for loud music at 100% digital volume, I output 24bit signal to the odac(whatever the actual music format), and adjust the level on the computer(foobar, my EQ, or whatever). I went for that because the O2 can go from almost nothing to about 0.7dB channel imbalance on my device, and has the bad taste of doing it on the same side as where my headphone is already imbalanced on most of the FR. so I set it up for good, looked with a voltmeter that the imbalance was kept low because I got lucky and found an area of the knob in that loudness area where I could get ok balance(a little above 0.1dB), and then used that to try and measure my headphone to make a compensation and match left and right a little better. that EQ would lose some of it's purpose if I kept changing the level of imbalance with the O2's knob(even if admittedly it's so small I shouldn't care). so for that specific idea, digital level setting is really convenient and that's what I use. but again with different gears I might do something else.

 

[gregorio]

At work, we use professional sound equipment for large sound-systems and i know the common logic there is to always have the amps at full, preferring to lower the volume digitally. When I inquired, the explanation i got was that the amps loose "quality", or information when they turn down, whereas digitally, you still receive the full "resolution" of the sound, just more quietly. Somehow this doesnt sit right with my logic, i dont know why..

It doesn't sit right with your logic because it isn't really right. However, the difference in practice is probably very little, to the point of being inconsequential. In large professional sound systems it's often impractical to adjust the amplifiers (for various reasons, including the likelihood there will be several of them and they'll usually be located somewhere other than where you need to adjust levels), instead the amplifiers are set very high and the desired level achieved by mixing into this fixed amplification level. Amps will typically produce more self-noise the closer to max you set the output but as a fixed very high/max setting is a common professional large sound system requirement, the pro amps designed for this type of installation are specifically engineered for it. Not so with consumer amps, although how much more self-noise and at what point it becomes audible will depend on the individual amp. Typically you'd get the best results by setting your digital output to 100% (or down as low as 90% if you want to be ultra-cautious) and then set your amp lower. This would in theory probably give you higher fidelity than your current settings (50% digital output), although if your amp is good quality then the difference could be fairly negligible and probably some way below audibility. The only way to know for sure with your particular combination of equipment (laptop, DAC, amp and HPs) would be test, blind or double blind if possible.

G

 

[adamlr]

i thank you both