Power amp under 500...

If you are looking for SS - the B&K EX-442 or 442 Sonata (later version) is an awesome sounding amp that is underrated imo...I owned one many years ago and it is extremely tube like but dynamic too...200w into 8 ohms, 360w into 4, 75 amps peak to peak...worth checking out if you can find one used, thanks, Louis

Either amp is fine. You'll do well with whichever you choose.

Go an extra hundred
Look for used Rotel RB-1080. Decent balance of strengths,not old,easy to sell.

I would look into an Aragon 2004mkII...I know it's only a 100 watt amp but believe me it will drive most anything...it's like some say "they are like a baby Krell" and built like a tank! you could probably find one on A'gon for in the $500.00 range...and if you want to spend just a little more ($600-700) definately look at the 4004mkII

Go with the Adcom. I have an Adcom pre-amp.