It's been more than a month, looks like this thread has cooled down, but if the OP hasn't taken action yet I may be of some help. (In fact I just subscribed to be able to do so, so hi everybody).
If not, others may still benefit from what I found.
My contribution is not on the SST vs SST2 question, but on the 4B vs. 7B question.
Looking for an amp for my 802D, I found a Bryston dealer that was extremely helpful (I'm in the Netherlands: it was Jan Horstman from Holland Link Hifi).
I considered and listened to 4BSST2, which already proved to be a big improvement over the amp I owned then.
Then I considered vertical bi-amping with 2x 4BSST2. So Jan brought me a second one (he's about 150 km / 90 miles away; ok this story is not about Jan but some credit is due
).
The beauty of having 2 4BSST2 in your home is that you can bridge them and have more or less the equivalent of a 14BSST2.
In other words, you can compare the virtues of bi-amping to those of simply having more power.
At first the bi-amping sounded nice, but then I payed attention and checked output levels.
One of the amps had a slightly louder output (I think it was 1 or 2 dB) and if you put that on the mid-high section (I had to do horizontal bi-amping for cabling reasons), it came out on top in the comparison. Reversing the situation eliminated the advantage of bi-amping. So it was clear I was not going to spend my money on a second 4B in biamp configuration.
Next came the 2x4BSST2 bridged configuration. That was another story! Now the 802D's were starting to show their true potential. I started to hear things I had never heard before!
This led me to a test run of the 14BSST2 (I think this time Jan and I exchanged gear from the booths of our cars at some halfway meeting point ...).
Internally, the 14BSST2 is very similar to a pair of bridged 4BSST2.
(forgive me, you all know that of course, this is a Bryston circle).
It sounded better again than the bridged 4BSST2. I can't find my notes right now, but when I say better I mean the "holistic" experience of the music rather than some isolated quality of it.
So I ordered the 14BSST2. Then, thinking about some practical issues, and looking at the limited price difference between 14B vs 2x7B, I quickly changed my mind: without having heard them (this is where Jan couldn't help me), I ordered a pair of 7BSST2. They didn't disappoint me. I never did a head to head comparison between the 7BSST2's and the 14BSST2, but I immediately had the impression that dynamics were better from the mono blocks.
So, this concludes my story of how I learned to appreciate the value of dynamics in music reproduction! Since then, I can always hear when a system is short on power. They often are...
No need to say (I hope) that all this is not just about playing loud.
Well maybe it's about playing loud without sounding 'loud' - to most people loud means distorted.
In case of undistorted playback you only notice it gets loud once you try to have a conversation ...
Nor is it about a particularly demanding kind of source material.
A solo grand piano or voice is all you need to demonstrate the differences.
(Yes, Santana 'Supernatural' tracks also do it
).
Bi-amping the 802D may still be a good idea, provided you start with sufficient power.
It would be 'interesting' to hear them on 4x7B.
But for me the interest would be academic: 'just' a pair of 7B's leaves me nothing to wish for.
(well, later on I tweaked my power lines and got some kicks from that but that's another story)
My gear: sonos ZP80+Benchmark DAC1Pre/Tentlabs b-DAC+Bryston BP26+7BSST2+802D
Interlinks Grimm audio TPM. Speaker cable Vandenhul Teatrack (biwired)
Hope this helps!
