has been to many requests, everybody have their own preferences about amos, especially speakers, i heard good things about Diamond, but I like my MBquart Premiums for domes with bass, depends what music, and frequencies you are listening.
Amplifiers, well there are some 5 channel amps on the market, but many of them would not put out more than 300 watts for subwoofer channel, you better off getting, and separate mono amplifier for subwoofer, that way you could have decent 4 channel, and if you are dissappointed you don't have to replace the whole system
just my 2 cents
Yev