First off if you find a 6 channel amp I guarantee it won't be cheap. I don' think I've ever even heard of a six channel amp. You may be able to find a 5 channel, but again I'm sure it won't be cheap. As far as your as a 4 channel goes you need to post more info. What speakers are you pushing and what type of power do they require or do you want going to them? On the suggestion side of things: You can go with a set up with more than one amp. In my current set up I only have a front stage with 2-5.25's and 2 tweets running off one amp and then I have my subs running off another. I think this is your best option and if you're just looking for good quality sound and aren't trying to win competitions, I suggest staying withing the power requirements of your speakers and just buying a name brand amp in your price range. Of course if you provide the power requirements then you could end up with more suggestions.