A little bit confuse on what is being ask here
If you’re referring to getting a 2 channels power amp to be connected directly to the pre-out of the AV amp front L/R?
Or are you referring to replacing the power amp above with an integrated amp instead?
Suppose your main purpose is to get a better music re-production from the AV amp.
If so, instead of doing the above 2 option, there is one other alternative where you can get a pure music re-production without having to pass through all the AV amp electronics.
In the market, there are integrated stereo amps with a HT by-pass input (ie effectively by passing the pre-amp section of the integrated stereo amp).
CD player to intergraded stereo amp.
AV amp front L/R pre-out to integrated stereo amp HT by-pass inputs.
When playing music, only turn on the intergraded stereo amp.
When playing movie, turn both amp on & set the integrated stereo amp input selector to HT by-pass.
(this effectively switch off the integrated stereo amp pre-amp stage & uses only it power-amp stage).
One such amp for your reference (
http://denon.co.uk/DocumentMaster/UK/Bed_PMA-1510AE.pdf)
Go to page 12 – power amp direct (also page 13 on how to connect btw the 2 amp).
Other than Denon, there are a lot of other brands integrated stereo amps offering the same functions (although some will call this in different name).