After buying a reasonable pair of budget headphones the other year (Grado SR80i), I have been interested in what difference a dedicated headphone amp might make over the socket on a 30 year-old Rotel integrated amp. The answer, it seems, is a fair bit. (Well, duh, as you might well say.)
Schiit Audio (yes, pronounced like that) have produced quite a number of headphone amps, primarily for use with their DACs and using computers / iPhones as a music source. But over the last few years they developed the Magni head-amp series of which the latest (Magni 3) has pre-outs as well, so it can act as a pre-amp using the tape in/out connections on hifi amps; I had two sets of interconnects after getting rid of a tape player, so no further cash required. Schiit also have a philosophy of building in the US (so great, apparently) and keeping prices down as much as possible. So at £110, and after weeks of reading YACF-like arguments on HeadFi & other forums, I bought one this week & got it today.
Blimey. So much more resolution of details, but not bright (the Grados seem bright-ish anyway); a bit like the difference between a good print of an oil painting against the original oil itself. I sat this evening with a gormless smile at anything I listened to on headphones. As a pre-amp the difference is not quite so great, but noticeable and rather good. It's about instrument timbre & recording room ambiance, really; much more involving for the listener.
It's a small box and obviously built to a price, but the money seems to be spent in the right places inside (I know absolutely nothing about this, only the sounds that emerge down the line). Really pleased. All I have to do now is work my way through my records & CDs again for a few years.