It's upgrade time...
Just got an ex-demo Arcam Alpha 10P-3 power amplifier.
I'm using this to drive the front (L/C/R) channels. It has about 160 WPC @ 4 ohms, providing a power increase over the AVR300 (100 WPC x 7). And by offloading the front channels from the AVR, it leaves more power available to the surrounds as well. This is good since my Dyns love power.
But that's not the best part. Tha Alpha 10P is a very high quality and very musical power amp, costing almost as much new as my AVR300. Compared to the AVR300 it has much tighter and more refined bass, and the mids are more detailed making center channel dialog more clear. It's also more punchy and dynamic. With this amp the whole system sounds much improved, and integrates with the Sub better (which I didn't expect).