Got everything through a mix of online and store, and someone who knows this stuff helped me hook it up.
The strange thing is Marantz's customer service told me I could biamp the fronts, center and surrounds. Crutchfield said I couldn't, and they ended up being correct.
Not that it's probably worth it, but just out of curiosity, How would an additional amp or a mono block(?] amp work in this situation?
You do not want to mix amps when Bi-Amping.
While I agree the benefits are likely minimal, there are edge cases for Bi-Amping passive Speakers, and that is in situations where the Speakers are difficult loads to drive. B&W is known for this problematic design. Impedance Minima below 4 ohms, challenging phase angles, all at lower frequencies...
Regardless, if you want to passively Bi-Amp your mains as they already are, no harm is done as long as the wiring is correct which it sounds like it is.
The Bi-Wire setup is a whole other story... it's is most likely completely pointless for 99% of use cases and is just a reason to sell more Speaker wire, which if you bought into premium brands can be very expensive for no gain.
If you wanted to add additional Amps, you would need to buy Four Monoblocks or Two Stereo Amps. Make certain they are capable of driving your Speakers, and remove the Amp 10 from the chain to your Mains. I would absolutely not mix other Amps for the Highs or Lows while using a different Amp for the other.
If you feel you have to Bi-Amp other Speakers "just because," you simply need to split each pre-out with a Y and run the signal to separate Amp Channels, then on to each Speaker Channel accordingly.
(If you can't tell, this is generally considered a silly practice by most of us here. Some schools of thought will argue otherwise, but there is ZERO evidence that this will pay any dividend for the expense.)
