Tubes vs Solid State

Going to a tube preamp is nothing big deal.
But going to a BIG tube amplifier IS a BIG DEAL.
I would love to have a pair of ARC REF600s to run my speakers..
But the power tubes are a big drawback.
If you are buying used, then you may have an issue with the tubes soon enough. Sending them back to ARC for retubing is a must unless you know and trust a local tube guru.
Personally if I have the money to buy the ARC REF600 i WOULD certainly do so for the great experience it could be.

So I say if you can afford the expense of retubing, go for the ARC anyday. It may be a really great experience.
(Or a moneypit)

Matching amps and speakers is important!

Take a look at this link:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php

The B&W 802 is designed to work on an amplifier that can double its power when the load is cut in half. Specifically, it has an 8 ohm midrange and tweeter, but the woofers are in parallel and so are 4 ohms. Not only that, but the woofers are 3 db less efficient than the mid and tweeter. To correct this, its expected that the amplifier will double its power into the lower impedance.

No tube amp can do this and so on this speaker, tube amps will have less punch in the bass. Now if you had a speaker that did not expect that of the amplifier, then you could get more punch out of a tube amp than a transistor amp...

Its all in the match. Of course its my opinion that tubes offer more music much easier than transistors do (I know of one transistor amp that is really musical but it retails for over $100,000...).

Another issue with 4 ohms is that the speaker cable is more critical and also that any amplifier driving 4 ohms (tube or transistor) will not sound as good as it does driving higher impedances. So if you are seeking musicality, you may want to consider replacing the speaker as well.

If you need to stick to the B&W's, stick with SS. In addition to all the reasons stated, tubes will be unstable with the loads the B&W need. I had a similar problem with my B&W's but I then sold them off to get speakers that were tube friendly.

I use the Rogue M180's with KT 120 tubes to drive Martin Logan Summits (which present a very difficult load to amp) with very good effect. You can retube yourself as there is a built in bias meter.

I would pay close attention to ralph's (atmasphere) response as it is probally going to be one of the best ones you will receive.