Setting up 2 power amplifiers to setup at once help?

@noromance With two amps of different gains the bass and mid/high sound levels won't match! That would hardly make for good listening! The OP wants to give his father the Denon and keep the Yamaha for the Polk's. I personally would do the opposite! I think the Denon will sound a bit better than the Yamaha! You are right though - the OP should sell either amp and get something like a Levinson ML3. Then he'd need a real preamp to match - like an ML1. Next, better speakers and onward down the rabbit hole!

@noromance  I own enough amps and preamps to equip a store! I have my favorites, too! Same for speakers - their sonic signatures are certainly more easy to discern!

I took a look at the manuals for the two amps in question, which can be found at hifiengine.com if one is registered there, and I calculated their gains based on their specified sensitivities and power ratings. In this particular case it happens that the gains of the two amps are almost equal, assuming the specs are accurate.

To be precise, the Denon’s calculated gain is 32.0 db, and the Yamaha’s is 31.24 db. Also, the Yamaha has input level controls, providing up to 20 db of attenuation in 1 db steps, and the Denon **might** also have input level controls. Input level controls on the Denon are "only provided for versions other than USA Canada and multi-voltage versions."

Finally, I took a look at the manual for the speakers and it confirms that they are suitable for biamping (when the jumpers are removed, of course), meaning that the low frequency and high frequency sections are not interconnected internally.

Regards,
-- Al

@almarg Thanks Al. Rock and roll!