What qualities do you look for in a good amp?

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

Look for an amp that doubles it power (watts) as the ohms are halved. This is a sign of a stable amp that will drive almost any speaker load.

IE:
200 watts @ 8 ohms
400 watss @ 4 ohms
800 watss @ 2 ohms etc.,etc.

Like Rockvirgo said, the heavier the amp, usually the better... this translates into a larger power supply and more $$$.

Short list to start with: Audio Reserach, Bryston, Krell, Mark Lenvinson, Pass Labs.(only to name a few) These are all high quality, well made amps, by 1st rate manufactures.

The final choice is what sounds best to YOU, not the BS the salesperson tells you. Good Luck!

I agree with rockvideo.Let me add some specifics.Some of the amps mentioned by Ig40 did not work for me.You need an amp with big dynamic range no feed back and reputed to be reliable.I have been happiest with Gryphon and YBA amps.

All excellent responses. There are many factors that go into purchasing an amp. You have to ask yourself a few fundamental questions.

1. How much power do I want?
2. How much heat do I want to put up with?
3. How much space do I have for the amp?
4. How much do I want to spend?
5. Tube Vs Solid state Which sounds better TO YOU!!
6. Do I prefer a neutral sound or a euphonic warm sound?
7. What are the other components in the system and how can
system synergy be achieved?

If you aswer these questions honestly you can narrow down you search to a few manufacturers and then auditon them!!

What to look for. No particular order.

1) Customer service dept readily available.
2) Stable reliable company.
3) Few models used up for sale.
4) Input impedance high enough to allow use of tube pre-amp.
5) Power rating stable into 4 ohms.
6) Protection circuitry that prevents failure due to clipping.
7) Ability to throw up a open sounstage and image precisely.
8) No excess energy in the bass/upper bass/lower midrange.
9) Highs that sound real without ripping your ears off.
10) Tonal accuracy in the midrange that produces palpable voices.
11) Binding posts that allow use of spades/bananas/bare wire/bi-wire.
12) Adjustable input sensitivity.
13) Reliable proven design.
14) Balanced circuitry that is truly differential.
15) Good resale value
16) Available in black or silver. No glitzy appearance.
17) Moderate heat to keep your room cool in summer.
18) High dynamic headroom.
19) Quick warm up time- under 1 1/2 hours to enjoy the sound.

Anything else??