running audio research d300 bridged

You are better off calling ARC. I ran a D300 with a pair of 1.6's also. I listen fairly loud, but the power of the amp seemed almost limitless (I miss that amp). I was not aware that you could bridge them, so asking the manufacturer may be the best bet.

I can confirm what Elizabeth stated from experience with the older ARC amps that could be bridged. The D52B, D100, etc. clearly stated if you bridge them, 8 Ohm is the minimum impedance. We fried at least one of them bridged driving an old pair of Magnepan MG1 (5 Ohm load).