I suppose my question is whether there is much audible difference in a DAC upgrade here or not in something like a double-blind? If there isn't much to be gained, I'd prefer to put aside the money towards more headphones. From memory, the issue with cheaper amps is distortion but I'm not finding myself able to notice any distortion while music is playing with the E10 on my HD25-IIs so I'm genuinely curious why I would want a more expensive amp. I'm also curious as to how a better amp improves SQ given what it does to the electrical signal. Is it an issue of colouring? Similar with a better DAC are we talking about colouring here rather than anything else? I get that the purposes of a DAC is accuracy, but am curious if cheaper gear really differentiates that much from each other)
Like I said, new to this and coming from a Physics background (not a sound one, so I'm not sure if I'm missing something obvious) so genuinely curious about the benefits of more expensive amps here with respect to headphones that aren't that hard to drive with respect to technical details rather than subjective impressions (am as prone to the placebo effect as anyone else, which makes me sceptical of claims based on subjective impressions of equipment because I know that if I buy an expensive DAC I'll probably think it sounds better regardless even if the SQ doesn't really change). I read NwAvGuy's blog and am curious about evidence along similar technical lines for upgrading DACs etc.
Maybe this is the wrong thread to be asking these kinds of questions though.