peterpan said:
I... like a warmer full bodied sound.
Is it safe to assume you'll be upgrading speakers next? You're speakers are not warm sounding in fact they're more likely to sound too bright than too warm if partnered incorrectly.
peterpan said:
I play a lot of rock and metal.
As mentioned by Muljao NAD C368 as reviewed by What Hifi has "Lacks get-up-and-go" in against column which should disqualify it for rock and especially metal.
NAD C356 seems better suited to what you describe in this regard.
peterpan said:
I'm looking now at these amps, not other brands please.
peterpan said:
I saw at a dealer a second hand Exposure 3010S2.
Ok...
You've not mentioned source once. If it's a turntable then you'll need something with phono stage. If you need a dac than out of a few mentioned above only Cambridge Audio have this on board as standard.
I'd suggest a demo of all and that you decide for yourself. As you can see it's difficult to advise you when it looks like you're really confused yourself. Not saying you are, but comparing amps at 3 different price levels suggest you are. There's too many things we don't know such as your future upgrade plans, source, essential features, price of that second hand Exposure, etc.
As a rule of thumb, second hand £1,700 amp (when new) should sound better than £500 new one. But sound is very personal so no guarantee you're going to like it. I recently had a demo of £3,000 Quad source + amp which I simply wouldn't even consider at half that price.
All the best in your search. I know how frustrating it can be.