OK. I would continue powering the M5s with your Emotiva. From a power rating perspective, it's a great match for the M5s. Hefty capacitance in there for peaks.
I cannot see how you'd gain any benefit from bi-amping the M100s. Here's why: if you're sitting 12 feet away, they need 256 peak Watts to hit 108 dB SPL peaks. Say 60% of that power is bass. That's about 150 Watts. Of that, maybe 20 Watts is routed into the M100s. The rest is provided by the 800s. 20 Watts is nothing for the 1500. Heck, even 150 Watts is nothing even when powering the 180.
I would use the 1500-3 for the 100 and 180. I'd then trade in the QS8 for QS10 and power all QS10 from the 1500-4. I'd bet you'd hear a big difference with your surrounds.
