I guess that's why Mr. Murphy does not seem worry much about people using AVRs to drive his speakers. I am surprised by your experience with the 802D2 though as I would not drive them with any AVR. I don't listen at reference level, but if I paid 12K for them, I would want to be able to. If you factor in their sensitivity, assume nominal impedance of 4 ohms, to be able to play them at 85 dB at 3 meter, plus another 20 dB for headroom, no AVR on earth would qualify.
Let's play w/ numbers.
Let's say the 802D2 is 90dB/w/m (spec 90dB/2.83v/m).
B&W 802 Diamond Speaker System HT Labs Measures | Home Theater
84dB/3m/1w
87dB/3m/2w
90/4w
93/8w
96/16w
99/32w
102/64w
105dB/3m/128w
THX standard is a MAX VOLUME of 105dB for speakers (85dB + 20dB Headroom) and 115dB for subwoofers.
According to HTM, the Denon 3312 can output 225WPC x 2Ch driven into 4 ohms @ 1% THD and 143WPC x 2Ch into 8 ohms, give or take a few for "accuracy".
Denon AVR-3312CI A/V Receiver HT Labs Measures | Home Theater
The 4 ohm Phil3 is 85dB/2.83v/m, assume ~ 85dB/w/m:
79dB/3m/1w
82dB/3m/2w
85/4w
88/8w
91/16w
94/32w
97/64w
100dB/128w
103dB/256w
106dB/3m/512w
And yet I can play the Phil3 EXTREMELY LOUD in my 18' x 20' x 12' family room open to formal living room, kitchen, and formal dinning room with only a Denon 3312.
Dennis has played the Phil3 in larger rooms to extreme volume with ~ 100WPC/8 ohm amps.
Other than that, sure, I think most people would power their 802D2 with more than a single AVR. I've heard some people use the Bryston 1,000W monoblocks ($19,000/ 2 amps) to power their $15,000 802D2.
Some people feel that a $5,000 Arcam or $5,500 AudioControl AVR, which measures less power output than the Denon 3312, is suitable for their 802D just because it is a $5K Arcam or $5.5K AudioControl.
http://www.hometheater.com/content/audiocontrol-concert-avr-1-av-receiver-ht-labs-measures
http://www.hometheater.com/content/arcam-avr600-av-receiver-ht-labs-measures