What to look for in amplifiers

I’m pretty new to shopping for hifi components, and I’m scouting around for a nice second hand amplifier. Seeing as I’m new to this though, I don’t really know what to look for in amplifiers, especially second hand ones. How do I know if something is a good deal, and what are the specifications I should pay attention to???

General advice appears to be start with the speakers, then work backwards.

I can see the logic of this, no point spending money on an amp that will power a concert hall when you live in a small bedsit

Once speakers are sorted, that will give you some of the specification you need from an amp. For example, if you go for high sensitivity speakers, you may want to look at class A amps

ask 10 people for their advice and you’ll get 11 answers

On second hand equipment, bear in mind that electrolytic capacitors & some other components have a life span of around 20 years, so older equipment may need upgrading by someone who knows what they are doing

I agree with the previous opinion.
If you have loudspeakers that are not very efficient, then I would strongly recommend a class-D power amplifier based on Hypex nCore 400/500 or Purifi 1ET400A EIGENTAKT. You will be extremely satisfied with that, they sounds fantastic! They don’t cost a lot of money and they leave most of the competition behind!
I don’t know how these amps sound with very sensitive speakers, I have no experience with them. But they may also be very good at such.

I don’t use a preamp. My Volumio streamer is connected directly to the power amp.

regards
rust21A

It’s a bit like asking what car should I get? As the other replies have said that depends on what you intend to do with it, how many passengers etc. Then beyond the functionality you’ll no doubt have personal taste in what you think sounds good and that can’t be described in simple spec’s.
So to offer suggestions: Get your speakers. Base your short list of amps on what they need to be driven properly. There are lots of vintage HiFi groups on Facebook etc which can be great places for info, advice and locally available product. HiFi Shark and other websites can help with reviews, price comparisons or sourcing something if you narrow your search down. As andrewnorth suggests:

…and finally if you are spending a bit of money, take your speakers to audition the amp or arrange to loan it for a test at your home.