ARC 100 Mk11or Conrad Johnson 11a?

I have not heard esl's with the CJ, but the ARC did an excellent job with my esl's. I ultimately went with another amp (Mesa Baron) because of it's flexibility and the fact that I was able to trade other equipment, parting with less cash. I would have been very satisfied with the ARC. It's a very fine amp in every respect. Prices seem to be attractive right now, maybe because the MkIII has come to market.

I have not heard that particular conrad-johnson, but the vt100m2 is one of my all time favorites. I've been very happy with the build quality, sound and support on mine.
Arc's tend to be more accurate and transparent, but conrad johnson's tend to be warmer with wonderful 'alive' midranges. I used to own the mv-50 which is a distant ancestor to the premier 11a. I thought the mv-50 was wonderful with my magnepan 1.6QR's.
Take care,
John.

Hi, I own ARC vt130 and have heard ARC100mkII at my house.
My experience with CJ is at dealer showroom.
They certainly sound different, but I don't think it is an "clear" upgrade. simply a sideways move ! ARC was very neutural, CJ was very relaxed and "great" midrange. I thought the VT130se was better than VT100mkII. More bigger, enveloping sound.
hope this helps.

How much power do you need? The ARC has more dynamics, more spacious soundstage, better bass, but its upper mid/lower treble bites a bit. The C-J is more seamless, finer textured, more midrange body, but sounds smaller/less powerful; should also be cheaper by 20-30% used. Are you only looking at tubes? Marsh A400s-pretty great for 200 watts/ch solid state.