What Power Amplifier Should I Buy?

@kevemaher thats why I recommend not using them as monoblocks, which is what Bryston is talking about. In this case they are bridged and each amp becomes one channel and doubles the power into 8 ohms. Try to find specs though on what they put into 4 ohms when bridged. It’s not recommended for speakers like Revels.
If you use one channel though from each amp to power the highs and lows of a speaker you let the amplifier ‘see’ a much easier load than if it was powering the whole speaker, and offering much more headroom. Active speakers (like ATC) have an amplifier for each driver in the speaker. You’re right, and as I mentioned in my first post you need a preamp with two sets of outputs or you can get a y-splitter for your preamp. Incidentally, when I had two 2.5s I tried them in this configuration as well as bridged monoblocks, powering the Revel 228 Be. It sounded ok as monos but not as good as the other way. A bit muddy. And two amps definitely sounded better than one, but the difference was not huge.

I don’t think you could go wrong with a 3B or a 4B, but I was looking at it from a price perspective. Probably cheaper to pick up a used 2.5. But also, from a power perspective, 2 smaller amps may be better than one larger. The 2.5 is conservatively spec’d. It’s basically a 150/300 w amp into 8/4 ohms. So biamping, at 4 ohms you’re getting 300 w/ch into the mid and tweeter, and 300 into the woofers, and each amp channel sees an easier impedance load. With something like a 4B you would get 500 w/ch into each speaker and it will see the combined load of the whole F208.

The BP17 is great with the 2.5, best match I had with those amps. There is a brand synergy there for sure. I haven’t heard the BP19 or BR20. The Benchmark LA4 is one of the best preamps I’ve ever had, especially as far as neutrality goes. It is a gem and at its price a tremendous deal. But for synergy with Bryston amps I’d probably get a Bryston preamp, if it were me. Plus as you mentioned you get the dual outputs.

Lastly, another option if you want to stick with Bryston and/or save some $$ and shelf space, the B135 integrated has preamp outs.  So you could use that with your 2.5B to horizontally biamp.  

The CODA 07x preamp also has dual XLR outputs (I think it also had an RCA).

It is a warmer tubey sounding preamp than the LA4. I kept the LA4.

My guess is that the dbx equalizer and sublime crossover have more to do with the lack of dynamics than anything else. These are both low cost devices with inexpensive opamps. In the case of the equalizer, you have dozens of opamps and cheap slider pots that you are running the signal through. 

@jaytor Yeah, I have always had concerns about the EQ. But some form of EQ is needed to help tame some of the FR variations from the room.

I have traps which are very effective. I don't need more, except for the floor to ceiling mode. But the "rules" prevent me from doing that. I have worked very hard at positioning the speakers and the sub to get the best FR, but there are still +/- 6 dB variations in the bass. I am restricted to near the present locations. I have tried a miniDSP Flex. It doesn't affect the time domain at all and is barely better than the analog EQ. I ditched that. And I enjoy the idea that I have an all analog signal path (except for the CD/DVD and music files).

So the dBx EQ is a somewhat "necessary" evil. I could live without it, but the engineer in me strives to have as perfect FR and TR (Temporal Response) as I can manage to obtain.

The XO does a very good job, far better than the Rane I once used. I don't like the idea of running the f208s full range and band limiting the woofer. However I haven't tried this in a while. Might be worth a shot.

Are you aware of any reviews on the Sublime XO?

Very helpful advice. Thanks.