ARC VT200 or Sonic Frontiers

I am looking for a good tube amp(?) to drive my Martin Logan Prodigy's. I am seeing ARC VT200/100's and lot's of Sonic Frontiers stuff here on Audiogone. Does anyone have experience in this area? Does the new mkII version of the VT200 sound better than the old (all tube version). I can't audition these amps so any help would be great.
Listened to the VT200 and found it smooth & effortless but lacking in the slam department. Ended up buying a Power 2 that was not as effortless as the VT200 but made up for it in other areas that were more appealing in particular, soundstaging.

That's as much comparision as I am able to offer, hope you find the right match for your ML's.
I am also interested in the VT 200 but there have not been many responses about the unit here on the "Gon. I wonder why? I have the VT 100 mkll and also wondered if the VT 200 mk1 was better or a Conrad Jonson 8 ...(need to drive my Infinity RS-1-B's)
I'm a longtime ARC amplifier fan. To me the vt100m2 stands as one the the best amplifier's I've heard at any price.
I recently borrowed a vt200 from a friend* to use with my power hungry eidolon speakers. I had been wanting to try out a large tube amp with them.
* kurt at - he still has it for sale

I took it home & I found that it was indeed a superb sounding amplifier but it didn't have the slam that I wanted. The eidolon's are the most difficult speaker to drive that I have ever owned. My reference amplifier is an Ayre v-1x which puts out 400w into the eidolon's 4 ohm load. The vt200 has a typical midbass emphasis and 'powerhouse' ARC sound. It was quite nice. If I didn't already own the ayre I would have bought it.

I have also hooked up a vt100m2 to the eidolon's and noticed that it was a little sweeter sounding, but did not have the soundstage of the vt200. The vt200 put out one of the largest soundstages I've ever had in my setup. It seemed to make the images go a couple feet past the walls. There was also this foundation of sound that is missing from the vt100. The vt100 sounds great, but it's soundstage is limited to the space between the speakers (9 feet). The 200 can deliver a soundstage that seems a good 20 feet accross. The ayre can do this too, but you lose a little of the tube liquidity. The vt200 did not have the transparency, weight and power that the ayre has. I'm primarily a tube fan, but I do like the ayre and pass labs amps.
Rwd- I cannot understand why more is not written about the VT 200 either. I am really wondering whether the new model VT's with the SS input stage is better than the all tube version's. Anybody out there ever compare ARC to Sonic Frontier? Anybody tried the new ARC 200 watt mono's?
Cmo: If you are really serious about owning ARC amps, you should consider calling ARC (non-toll free number and ask to talk with Warren G their chief "listener". He is very familiar with the entire amplifier line and the product changes. They have some very serious speakers in their listening rooms (see factory tour-linkable thru A-gon) and he is a very enthusiastic person to converse with. They also still support any product they have ever produced.
I own a VT200 Mk1, which recently did some mods inside the unit:
-replaced the infinicaps and wonder caps in signal output coupling caps and power supply bypass for stealth caps
-The original power cord replaced by transparent reference xl power cord.
- Replaced all tubes by using svetlana special edition

those improvements transform this extremely good amplifier into a new one vastly better than original.

-Much better low end, tight bass, extremely dinamic, some veil removed which mades a extremely accurate amplifier.
- the mids are to die for, clean as the best, articulated and effortless.
- top end is too another area vastly improved, in fact I don't know from what I heard a better top end out there.
- the soundstage increase and much better defined.
the system is:
VPI Classic turntable/dynavector vpi special cartridge
Audioresearch ref 3 preamplifier
Meridian G08 CD player
Nordost quattro fil balanced interconnects
transparent loudspeakers speakers cables
I had a SF Power 2 a few years ago. I would NOT recomned this amp. Sounding like SS, and had an upper bass bump that was very annoying.

"I had a SF Power 2 a few years ago. I would NOT recomned this amp. Sounding like SS, and had an upper bass bump that was very annoying."

interesting. I used to own ARC VT-100 I/II/III and SF Power 2/2SE/3, I would not characterize any of them as having a upper bass bump and Stereophile measurements confirmed it. must be your setup.