Bryston 7B3 vs 4B3: Extra Cost Worthwhile?

Glad I saw your post the day after I put my Bryston 4B3 into my system as I would have otherwise started stressing about your issue. Just a note, had planned to biwire my Tannoy Cheviots with Analysis Plus Black Mesh Oval 9 gauge cable as I have a long run to one speaker, and found the Bryston posts only will accommodate one spade, so am going to have to wait to have each pair of cables reterminated into one on the amp end.

The Bryston sounded immediately better than my Parasound A23+ as soon as I turned it on and expect it will sound even better in 100 hours or so, sonInsuspect you will be happy either way you go. So far the bass sounds much tighter, and I am hearing more detail and greater instrument separation, including instruments I never noticed even in some old favorites that have become standards For auditioning new gear. Also, having played jazz and seen a lot of jazz live, I was happy to hear an improved gritty realness in saxophones mixed low as backing instruments that I thought my pre-upgraded system already handled pretty well.

If you somaettle on a Bryston, I hope you post on your thoughts on preamps as a new one is next on my list (have the Parasound Halo P6)

Recent info from Benchmark Support   

No worries with the AHB2. In mono, it will drive down to 1Ohm. Into 6Ohms, the bridged AHB2 will output 480 watts.The input impedance whether stereo or mono is 50kOhms The amp will draw up to 8 amps. 
Also the specs state that distortion at all levels will be identical to Stereo mode and SNR will be 3db better in mono mode and that it will sound the same in either mode with the difference being available power in mono.   

I would be interested to know Benchmarks thoughts on damping factor. Assuming the same 10’ cables are used, I believe the damping factor is halved, down to 85 bridged in to an 8 ohm speaker.

From Benchmark web site:

Nevertheless, it is possible that this 0.2 dB variation could be detected in a A/B or A/B/X test between two amplifiers having different damping factors (one with a damping factor of 100 and one with a much higher damping factor). If we match the amplitudes at 3 kHz, one amplifier could be almost 0.2 dB louder at 119 Hz using our example speakers.

The general rule of thumb for A/B and A/B/X tests is that levels should be matched to better than 0.1 dB. If this is not done, the level changes can be detected by many listeners.

This seems to conflict with their statements to you and does not address any issues with less bass driver control. The solution is to use a much shorter speaker cable to increase the damping factor, however, that involves additional cable cost albeit nominal if you use the BM cables.

My current speaker cables are 6’. 
 

I haven’t decided what I’m going to do. Benchmark insists that unless I’m clipping the amp there is no reason to get a second and that I will not hear any difference other than the ability to play louder. 
 

Still considering 

Bryston, CODA, Pass, Ayre, and Accuphase. 
I find amplifiers the most difficult component to select.