An Aragon 8008BB drives my N805's just fine.
I have not heard the Classe but IMO the Krell is a bit too bright for your speakers. It definately has relentless power but I found it very bright with my Dyanudio audience 82. The combination was really bad and I do not think that the Dyns are brighter than the B&W...On the other hand, I am not sure but you could probably solve this problem with some good copper cables...I like the Krell but it needs careful matching to sing
I have not used your model B&W's, but have used the CAP-80 and CAP-100 in the past with Thiel and Magnepan speakers...with great results. I had tried the Krell integrated and found it was hard to listen to for any period of time...not a good sign. I've been lucky enough to have some good to very good audio products, inc. the CJ ART, and now am using the BAT integrated with the super tube option. That said, I have great respect for all of the Classe integrated amps.
Just hooked up a Kav300IL to my system last week, bypassin my Proceed AVP-S and Linar 250 but retaining the speakers, cables and source.
In one word, dissapointing.
I also use N804 and N805's and would NOT recommend this as an option. The source is a Sony S9000ES using Transparent reference XL IC's, Audioquest Python XLR from amp to preamp, and Transparent Plus Bi-Wires for speakers.
I have however, heard the kav300IL in a system with Vienna Accoustics Beethoven's that sounded very nice, but only at lower volumes.
The Krell 300i sounds bright and hard with the N805 while the newer 300il sounds bland and grey, neither of which are suitable. The Classe CAP-151 should be a good match but I was once told by a Classe sales rep to not bother with the 101 becasue of it's low current power delivery. It is also worth looking at the Sim Audio i-3 and i-5 which work very well with B&W speakers.
for what it's worth I'm auditiopning a Krell TAS 200x5 with N802's for 2 channel, and N804's and HTM1 added for HT. I've found none of the harsh brightness others reference (using little ol' cobaltcable ultimate speaker cable...solid copper)and when I spoke to Krell and B&W they each foavorably referenced the other as showcase partners for the Nautilus and KAV lines...
If you're happy with the Musical Fidelity sound, consider bi-amping as a cost-effective option that will maintain the system's sound. I had a pair of A3cr power amps controlled by the A3cr pre driving B&W 602. Though the 602 is clearly not in the same league as the 805, which I considered, the extra dynamic headroom from two amps made a wonderful difference. The the system had shattering dynamics. My experience suggests that B&W can eat a lot of clean power. I also found the MF - B&W pairing worked very well.
Though I have moved to other speakers, I now have the Krell KAV 300iL powering the stereo. The 602 are still sitting around, and I hooked them up to the Krell for kicks. I did not find the partnering objectionable, but I don't find Krell to sound bright, either.
It could be the case that you cannot drop a Krell amp into the system and judge immediately. The Krell's famous iron grip, high current, push-pull, fully balanced design further breaks in the moving elements of a speaker. After this second speaker break in completes, the pairing may sound better.
I have no experience with Classe products.
I am quite new at this but my setup consist of Nautilus N805 and a Classe CAP101 newest model.
The CAP 101 has plenty of power for the Nautilus. If I had to do it again I would maybie consider the CAP 151 but I could not tell you why (I guess because it's the biggest of the integrated). Some thread above mentions that B&W and Classe and tunned together. My dealer told me exactly the same. I am to new to state the difference between the 101 and 151, I mean sonically. Everyone can read that the design is not the same. The 151 probably has more reserve and a tad more bass. It is also 500 more $$. My next step will probably be CP47.5 and a CA101 leading to CA201 down the road. Classe is not for the analytical, pencil and pad technical freak analyser person who only wants to hear how an amp can reproduce sound. It is on the smooth side and is never irratating. Many poeple pair the Cap151 with N805.
B&W doesn't design their speakers with ONE manufactures amp. They use (or have used) Krell, Chord, Mark Levinson, Classe, etc. when designing speakers. One point of intrest is that they stopped using active preamps because they found them to be too colored. They were using a Mark Levinson 32 then dropped that for a passive (not sure on manufacturer) and then on to a custom built stepped resistor attenuator. On their relationships with other manufacturers I know that they import Rotel to the US market and Classe to European market. They stopped using Krell at shows not because they make bad amps but because they started making speakers which would infringe on B&Ws market. The same with Levinson when Revel came out, you notice Classe doesn't make speakers (yet).