[mulder01]

I keep reading all the time people saying X amp sounds better with X headphones on lo gain / medium gain / hi gain but as far as I can see it should make no difference unless you actually run out of power on a certain setting - can adding (for example) +6db of pre gain on a switch then adding 20db of gain (or whatever) on the volume knob sound any different to 0db of pre gain on a switch and 26db of gain on the volume knob?

(Not 100% sure how it works inside an amp) but Is it possible that the listener prefers the sound of the amplifier with more / less of the signal being amplified through the pre gain switch than the volume knob? Do the signal paths vary enough for this to be a possibility or is it likely placebo?

 

[icebear]

If the amp has a crappy volume pot, there might be some differences depending on the position of the pot.
I have a GSX-MkII with a DACT attenuator and I can't detect any differences.

 

[castleofargh]

it's hard to give one single answer.
-as said above, with problem volume pots, having too much gain is clearly a bad idea, I can think of a lot of amps that have channel imbalance at low volume levels. and higher gain would just mean getting closer to those problematic areas of the knob when setting for the same loudness.
-having too much gain would probably also lead to more noise. but on most good amps, I doubt it's any concern.
-some designs like the O2 may just end up clipping, but that's because the high gain was originally added to use with weak portable DACs as sources.
-having not enough gain would simply mean not getting the headphone loud enough, so I guess anybody would be able to determine this and switch to a higher gain setting.

-a few amps have a different impedance at different gain settings. that could definitely lead to audible differences on some headphones.
-it's pretty much impossible to test 2 gain positions properly without something to volume match, so obviously, "louder is better" will fool a great many people who can swear on their mother's grave that high gain has better bass, details, and soundstage.
 
 
all the amp designers I've asked so far, have told me to use the low gain and go up when the sound isn't loud enough.