I’ve seen people state both that they so not influence the tuning as long as they deliver the same power and others stating that they can make headphones “sound warmer” or “brighter”. I don’t see how that would happen though and a lot of audiophiles just hear things that I feel aren’t there, like some noise difference between the Apple DAC Dongle and a 500 EUR DAC using an off the rack chip.
Take this comment from ASR:
Amps are more likely to make an audible difference than most DACs, but that certainly doesn’t mean there are audible differences between most amps
I’m talking purely about AMPs here, not a DAC combination.
Technically, what amp do is gives power to headphone over all frequency input without changing its source and without gives noise to sound. Is that hard? Honestly, no way that hard, it is classic technology. If people say that it change sound, then the amp alternate the sound by changing its frequency response or phase response and of course intended by manufacture. Is that snake oil? If you use sound driver from laptop, of course that is intended to be bad, but if you buy cheap china amp out there, probably will sufficient for your headphone, no need fancy hundred dollar amp.