Joe,
I agree with you big time. This RA-1 that I have been listening to for 17 years now sounds absolutely wonderful with my Grado HP-1 headphones, (and also with several other headphones I have paired it with). I am sure that one could find more expensive parts to assemble it with, and I am sure that there are many amps that would blow it away if measured with scientific instruments.
However, to my 40+ year old ears, the sound is excellent. In fact, I doubt if I could do an A-B test with amps costing 3 times as much and figure out which channel the more expensive amp was on. I would say that for most people over 40 years old, paying more for an amp might not yield a noticeable result, especially if one owns Grado Headphones.
On the other hand, if one is much younger than 40, or if one has a really well-trained set of 40+ ears, then, sure, many more expensive amps would be a worthwhile purchase, even with Grado headphones. Still, if one is over 40, if one owns Grado headphones, and if one is not a headphone expert, then this amp is a good bet.
By the way, to those of you under 20, please value your hearing and avoid exposing your ears to loud sounds (even loud music). A good set of cans will provide the full frequency range of human hearing without resorting to excessively loud volume. Concerts are fine, but do yourself a favor and invest in a good pair of earplugs.
You want to be able to appreciate a good DAC-amp-headphone rig once you are able to afford it. It is the ultimate irony to arrive at a finical stautus that allows you to buy virtually any pair of cans plus accessories and then realize that any money you spend beyond moderately-priced gear is a total waste because of the damage you have done to your hearing. Dang, I knew I should have worn earplugs to that Stones concert!
