Adding a 7CH AMP to Yamaha RX-V4600. Is it Worth it for AMP under $1500?

AudioVideo

I have a large stack of receivers in my basement dating back as far as a Heathkit AR2020 Quadraphonic Receiver that I built while I was in grade school.
Although, I have purchased many receivers throughout the years I have never purchased any stand alone Amps. My main systems current receiver is a Yamaha RX-V4600.
Would there be any real noticeable increase in sound quality by adding a standalone 7 channel Amp to my Pre Outs if I am only interested in spending less than $1500 preferably less than $1000?
If so, what models would you suggest?
I am driving Polk Audio RTi100 fronts, CSi40 Center, 4 RTi28 surrounds and PSW303.

Thanks for any advice.

fireshoes

A 7-channel would be nice, but I'd probably go for a 2 or 3-channel instead. Subwoofer is your system's glaring weakness though.