What qualities do you look for in a good amp?

I would first have to know what speakers they are to be mated with if I was going to aim for the best synergy.

I would then research what others have found to be the best match with the speakers I will be using.

I would then go and try to get an audition of the amp.

Lack of grain
Soundstaging
Detail
Bass

Those are all points I would listen for to see weather I like the presentation before purchasing.

Good luck!

Hmmm, I am not into silver yet, so I look for black faceplates. =)

This is like asking literally for "ice cream" when you walk in Baskin Robbins.

Seriously, I try to "listen" more than look. I will "look" at the spec sheet but that doesnt mean much. I like to look inside and see large and well constructed torodial power supplies, first and foremost. Then all the other "guts" like, voltage rails, cabling routing, Caps, boards, output terminals, output devices, etc. etc.

I think of a power amp as the producing element in my system. Preferably it will be the strong, silent type which can execute the most demanding of tasks without complaint or hesitation. Extending the analogy, the front end source component is the talent and the preamp is the director. The rack, cables, cords, spikes and room treatments are the props. The speakers are the stage.

My decision tree when auditioning a power amp flows from one must-have aspect to another. It begins with philosophical considerations:

1. Solid-state. For me, this is a cost, stability and reliability issue. If the best tubes were perfectly matched and cost the same as sparkplugs I'd reconsider.
2. Reputation. I take comfort believing there is a designer behind the product with experience and talent. An amp's popularity is a plus.
3. Pleasant appearance. The amp must look purposeful. Flimsy looking or unfinished parts convey weakness in execution.

Physical considerations:
4. Rows of external heat sinks. These are reputed to be expensive. Mounting them on the outside of the chassis seems to be the preferred method.
5. Sheer weight. Real-life power supplies are heavy. If it specs at 200 watts a channel but weighs only 25 pounds somebody's kidding somebody.
6. Number of output devices. More is better. While I admire an amp that can squeeze alot of performance from a minimum of parts, in the long run my money's on the unit that has so many muscles it never breaks a sweat.
7. Connectors. With the amp in place they must be reachable and not too difficult to tighten. With its own allure, gold plating is the icing on the cake.

Sound:
This subjective element is the hardest to pinpoint. When an amp is doing its job for me, it will sound smooth, effortless, unforced yet unrestrained, balanced, limitless, fast, quiet and balanced. All combined it will sound magical.

Enjoy your search.

I like the ones that just get out of the way.This is one that changes the signal the least from input to output. I like the romantic sound but not on every recording.Quiet is a major plus...no hum in the speakers. So far the ones that seem to do this the best IMHO are digital amps. They don't weigh much but are 50% more efficient than the average amp.Which means they only take in what the speakers need.Instead of giving half of their stated power to the atmosphere in the form of heat.

Good Luck with the Hunt