Rich; organic true balanced amp w good detail $6k

Since you said Organic I'll suggest Lamm ML1.1's or Lamm M1.1's used as the $7-10k used depending.. They can be a little dark but not like the BAT's.. Way more musical than anything listed so far. The Lamm's are single ended though with balanced inputs.

The VTL are very liquid and open (nothing obsured or blurry) but with slightly more emotion than the ARC you are using. I think you have to go to the VTL450 or higher to get fully balanced (Remember 3 times the electronics path for fully balanced designs).

If you wanted a more romantic sound go with the Manely 250's or 500... Manely errors on the more traditional side versus the clarity that the VTL provides. You might be able to go with his smaller amps which are a single ended design.

The bargain amp would be a Music Reference RM200 or the new RM300's.. these are really easy tubes to deal with (only 4 output tubes, long lasting, balanced design) Not Warm, the RM-9 MKI or MkII are warmer and excellent amps also. Less heat also because Roger doesn't drive the tubes hard..

I have owned two Sistrum racks and I found that in a very revealing system they start to strip away some of that magical midrange as a trade off for the detail and image placement. Throw a 1.5" maple cutting board under your preamp on the upturned Sistrum spikes and see what you think... Plus make sure yours are filled with the microballs to mass load the rack.

Bob_reynolds: Good Point about the output impedance of the Sonic Frontiers.. it might not match up with the Lamms as they are really sensitive. Typically less then 1volt to full volume

I've owned Lamm M1.1's and M2.1 and my friends fell in love with them but then I heard the VTL S400 releasized I needed some more clarity and also surpising the VTL went lower and deeper and it was definitely tighter.. I can't imagine the Belles comparing to the Lamm's as they are really addictive and some day I'm dying to get a set of Lamm ML2.1... If you run the Lamms in a home theater setup you better drop the center channel because there is no way you will find a matching tonal center channel amp... run Phantom Mode..

Sutts: The Lamm M1.1 versus M1.2 ..yes the M1.2's are better (not in a huge difference as he just used more currently available parts) and they provide like another 10 watts a channel. The biggest advantage are they are newer (since these run in Class A full time) Expect to see them listed for about $6000-7500 for Lamm M1.1's and somewhere north of 10k for M1.2's. Oh yeah and buy the 6922 input tubes from Lamm as they were like $25 each from them.... total no brainer bargain..

As far as the VTL amps.. 6550 tubes from VTL are about $60 each but you can get between 5,000-10,000 hours I out of tube the way VTL runs them... plus the best part is no matched pairs,quads, octets.... so way cheaper than ARC retubing... one tube blows, just drop in another. The new VTL450 signature has the computer controlled biasing which is awesome... similar tech to the S400 stereo amp. VTL no problem for home theater...

As far as Music Reference amps... I have owned the RM200 twice and I still regret selling it.. it's not as organic/seductive as the Lamms but it's more open on the top and crystal clear with even 2ohm control.. it only requires a Quad of 6550, or KT88's tubes which I recommend buying from Ram Tubes (Music Reference's company) especially the input tubes because they DC stress them which no one else does .. Music Reference amps aren't hard on tubes and tube that would be noisy in other amps are quiet in the RM amps.. The older RM9 required more expensive Matched Quads to achieve 100watts a channel or 125watt a channel in the RM9 MkII. These don't have the iron fist control of the RM200 (which can borerline on sounding similar to the high end SS Ayre amp in clarity and control) This might be similar to the Vac with the sparkle, and also without the constant repairs my friends have had with their VAC's (they sold them now and went back to solid state... after 3 roundtrips back to the factory..) Music Reference.. no problem for home theater.. Check out Audiocircle dot com for the Music Reference Forum, I'm sure you can post and find someone near you to hear these amps.. very minimalist but bulletproof design and they sound great!

Tvad: Great descriptions of those amps!
The Music Reference RM200 would have the clarity of the VAC but without the sparkle (very neutral, might not have enough flavoring for you), the RM9 with EL34's would be a little rolled on top and bottom, but the RM9 with 6550's would have better bass and more top extension but not as romantic in the mids (not as clear as the VAC's) (but not as tight as others or including the RM200 which is like SS on the bottom end).

I looked up on VTL's website and it looks like they have listed the newer version of the VTL450's which have some of the computer control circuitry in them for biasing. Maybe at CES this week it will be official or they will update the website. The S400 constantly bias during listening..As for heat... 16 6550c across two tube monoblocks generates a heat anyway you cut it, but in my small 16x12 room my lamms would heat the room 10 degrees in under 5 minutes.. Class A or Big Tube amps.. both are probably pretty close to the same heat output..

Your speakers are pretty effiecent and provide a high ohm difficult load that you should talk with the designer like TVAD suggested and find out what he recommends. The description TVAD makes for the Belles sounds like how some people descripe the Clayton equipment which I haven't heard.

Congrats on being able to make this kind of equipment choice... as this is the range of $$$ that products can be amazing across the whole frequency spectrum.

Some times Lamm ML1.1's show up which are 90watt tube amps (not hybrid) (not SET) and I'm sure they are amazing at approx ~10k and sometime 6-8k for the older ML1's. Don't buy Lamm's unless the owner has the original crates to protect them with otherwise you will have problems shipping them to Lamm should you need service.

The Lamm's are not a truely balanced design because Vlad doesn't believe it is necessary for consumer requirement as he can achieve the low noise with his single ended design. If you read his manuals, or an interview with him he will state this.

Drive and hear your friends Lamm's, and bring your preamp to make sure it can work with their high impendence.. You might end up with not enough volume increments because of the amp sensitivity. (I went through 3 preamps before finding one that worked correclyt.. Rowland Synergy IIi and my Theta Gen VIII worked fine)