I have Krell amps and Apogee speakers, I use the Sunfire theatergrand from it's balanced outs to the Krells, not a bright bone in it's body!
I use to run those same speakers through a Theta Casa-Nova with great results. You can run the front three channels balanced too if you'd like. Theta pre-amps are sweet and can be had for a song these days (less than 2k)
I never had any complaints with mine and would still be using one today if I hadn't upgraded to their Casa-Blanca II.
Be sure to give your Thiels lots of power. With Thiel to much ain't enough.
If you can find a pair of MCS1's with stands for the rear you'll have my old system, and oh what a system it was! I use to drive the whole thing with a Theta Dreadnaught (which I still use) no problemo!
I have a pair of CS3.6's, with an SCS3 center and some older AR surrounds. While my amplification is not up to your level (I have two Adcom GFA-555II's in bridged mono pumping 850w into each of the 3.6's, and an Adcom GFA-2535 feeding the center (bridged) and surrounds), I am very happy with the results that I am getting out of my Rotel RSP-1066. The store that I bought it from (Progressive Audio, in Columbus, Ohio) said that the Krell Showcase was their highest recommendation, but that if you didn't want to (or weren't able to) pay its asking price, the Rotel RSP-1066 was nearly as good for a far lower price. I would love to have all Krell in the preamp/amp department one day, but in the meantime, the Rotel/Adcom setup works well.
How do you like your Merlins with the Thiels? My AR's are nice sounding speakers, but their voicing is a good bit different than the Thiels. So far, in surround use, I haven't really noticed, but I would like to pick up an SACD player within the next year, and my guess is that the different voicings will become more apparent when I do.
Tom, thanks for the response. The Krell Showcase is probably a good choice since I have thier amp. I haven't played my Merlins since I got the Thiel 3.6s five years ago. They've been in storage waiting to be used for surrounds. I'm not expecting too much from them, except to give me a better sense of ambience. I currently own a Melos hybrid stereo preamp, so I haven't had a chance to listen to anything other than 2 channels. But, I'm getting closer!
I have a setup very similar to yours. I have Thiel 3.6's on the front, an MCS1 for the center. I have Krell KAV 2250/3250 amps. I use the Krell Showcase pre-pro that I got used on Audiogon for less than 3 grand. I have been extremely pleased. It works just as well for music as movies.
FWIW, I have since upgraded my amplification significantly to Theta Enterprise monoblocks on the CS3.6's, and Theta Intrepid powering the rest. I have also added a Velodyne DD-12 (great upgrade!). I still have the RSP-1066, but my next upgrade (after my Modwright tweaked Denon 5900 comes in) will probably be to either the Krell HTS 7.1 or the EAD Theatermaster 8800 Pro. I was incorrect in my prior post about the Showcase being my dealer's "highest recommendation." They really like the Showcase for the money, but sonically, the HTS 7.1 or Theta CasablancaIII woudl be their highest recommendation. Of course, they don't sell EAD.
Hummmmm...I like the krell pre/pro's, very much actually. I used to sell Thiel set up with Krell KAV250 amps and HTS processor. While the sound was very detailed and clear, some might think the trebble "walks the line" pretty thin, or close. Tastes may very. I've had clients comment that they didn't like the Treble match of Thiel 2.3's with the krell combo. But, then again the 3.6's are different speakers to my ears. It maybe a more solid match, and of course cabling will "season to taste" for optimum sound any time.
I'd give the Krell stuff a try in a heartbeat. But then I like their pre/pro's, and have gotten gorgeous sound for multi channel with them indeed.
Still, if you are woried about the top end balance, to be critical (or safe), Macintosh, Classe, Aragon, maybe CAL Probabaly EAD 8800, and Theta's top would probably "steer you safe" if you have any concerns there. All these offer superb surround processing and refinement. The AVM20 I've not heard, and am a little sceptical. But that's only because I've sold Anthem/Sonic F over the years, and just didn't hear the AVM2 sound good in any setup's I breifly heard(although that company had great products in the past, and now Paradigm owns). Although that may indeed be a great piece, I dunno. I still haven't heard any real solid reviews or demo's on that piece.
Personally, I've sold a lot of gear over the years, and have been around most all the lines. I tend to shy from the Lexicons', Bryston's, B&K's, Meridian's, etc. I think these sound more digital, warm, and or plain to my ears. Actually the Meridian is best here, but complicated, and not that special sounding if you ask me, but decent.
You'll really have to try to find out though. No other real way.
This is not a snap answer choice, as you know.