I am by no means a stereophile, but I am pretty sure this is the place to come for this type of advice. I currently have an Integra DTR 5.5 which is feeding an old (~15 years) Sony Reciever for 5 sets up speakers in Zone 2. Note that all 5 sets of speakers are not on at the same time. The Sony is acting up so I want to replace it. I believe the best replacement is a power amp.

First question is a power amp the right solution. Second, how much of a difference in sound quality would there be from the Sony to a moderately priced amp (say $750) to a better(say $2000) amp? Source is CD's (a Sony multi disc player) and a Squeezebox3. Speakers are proficient audio W670(?).

Thanks for any advice.