An AV receivers preamp section is lesser quality than the amp section. To many op amps and signal path length for the low the level signal before it is amplified.
A tube preamp (or SS) would provide better sound if the receiver has multichannel amp inputs. If it does, and you have a preamp w/ 2 outputs, you can use 4 of the AV receivers amps and bi-amp your speakers, if they offer connections.
A tube preamp (or SS) would provide better sound if the receiver has multichannel amp inputs. If it does, and you have a preamp w/ 2 outputs, you can use 4 of the AV receivers amps and bi-amp your speakers, if they offer connections.