Personally I wouldn’t do a 5-channel amp unless I was big into high-quality surround music. Short of that, I’d rather do a better 3-channel amp for the L/R/C and let the receiver power the rears. There’s a McCormack DNA HT3 available now for $800 (List $2300) that I’d jump on if you want a big upgrade to your HT amplification.
That said, if it were me I’d upgrade to something like a used Anthem MRX 520. Why? Well, as audiophiles we know the preamp is as or even more important to the ultimate sound quality of a system as the amp. So bu upgrading the amp you’ll likely get some improvement, but you’re still stuck with the preamp section of the Denon. By going to an MRX 520 you’d not only get better quality amplification but also a much better preamp and arguably better surround processing as a further bonus. Put all those together and the resulting increase in overall sound quality will likely far eclipse just inserting an amp in with the Denon. Used MRX 520s do pop up in the $800 range from time to time, which is only a little more than you were planning on spending on just an amp.
Anyway, two other options to ponder. Best of luck.
That said, if it were me I’d upgrade to something like a used Anthem MRX 520. Why? Well, as audiophiles we know the preamp is as or even more important to the ultimate sound quality of a system as the amp. So bu upgrading the amp you’ll likely get some improvement, but you’re still stuck with the preamp section of the Denon. By going to an MRX 520 you’d not only get better quality amplification but also a much better preamp and arguably better surround processing as a further bonus. Put all those together and the resulting increase in overall sound quality will likely far eclipse just inserting an amp in with the Denon. Used MRX 520s do pop up in the $800 range from time to time, which is only a little more than you were planning on spending on just an amp.
Anyway, two other options to ponder. Best of luck.