Upgrade Time

It would be a shame to drop $8-$10K on a power amp and pair it w/the Cambridge for the next couple of years. While I agree with all the caveats posted above(space, extra cables, etc.) separates are generally a wiser investment. 
Are you talking new or used gear? Either way, I'd rather see you upgrade both amp & pre. For example, get a Backert Labs Rhumba for $4K and your fav $4-6K power amp that pair well w/the Sonus Fabers and you'll have a blast instead of waiting 2 more years to hear what your new super-amp can do. Cheers,
Spencer 

What sources do you use other than the streamer portion of the Cambridge pre? 

Just one thought, start the upgrade path from the source. Separates will allow for this. Replace the Cambridge full function preamp with new DAC and line level Preamp. Providing the Cambridge amp it is driving your speakers satisfactorily use it till it can be replaced. The search for 'the' amp for your speakers can continue. Upgrades in the front end of your system will be appreciated till that purchase is made.

I’m getting amazing results for $5,500 in a 2nd system with some great, lightly used gear. Components and their used cost: Leben CS-300xs ($2,700) driving Forte III’s ($2,400) and being fed by an older Node2 ($400/new). For the money, or actually any amount of money, this is a really fun and satisfying setup. Don’t feel you have to spend the $10K. The key is finding fantastic component synergy.

Your speakers are 88dB. We had some here only 87dB and they absolutely came alive with the Raven Blackhawk. Played impressively loud too, in my 17x24 room. Unless you have a lot bigger room or listen real loud you will be fine with this amp, which is absolutely magical. Being integrated eliminates the "component synergy" canard entirely. Also eliminates one interconnect, one power cord, one fuse, set of Pods, etc. Add it all up, a Blackhawk with all that will still be well under $10k and sound far better than any separate amp you can find.

Separates only get anywhere by ignoring all this other stuff. The minute you account for everything the so-called performance advantage evaporates.   

Talk to Dave Thompson, he knows his tubes and will set you up with some great ones. Amp goes from great to magic with the right tubes.

If you do want more power, Audio Hungary.

@sbank  Your line of thinking makes sense. Basically you are saying the Cambridge DAC/Pre-amp will significantly drag down even a $10K level amp. 

I wonder if others agree with this? Is the CA 851N streamer so bad that I'd be better off spreading the $10K around to upgrade the whole system? I don't know what I don't know I guess.

@mesch I only use digital today through the streamer. I also have it connected to my TV but that's not a big concern right now. Thinking of adding a turntable later but that's just for fun to try out.

@millercarbon Thanks for the recommendation. I was worried my current 100 wpc amp might struggle a little with driving these. But I suppose pure wattage is not the only solution.