Question For Those In The Know About Audio Research Power Amps

I've flirted with ARC gear over the years, owning an LS5 preamp some years ago but never trying their power amps.

I've always had the idea that ARC tube power was a little lean and sterile and not in the Conrad Johnson style of presentation, with tube bloominess and that glorious CJ midrange.

Of course, I realize not all ARC amps sound the same and that some are warmer and more tube-like than others.

Anyway, I recently purchased an ARC Reference 110 SE, and really like a lot about what it does. Stage depth and imaging are excellent, it's detailed and dynamic. As if to reinforce the negative stereotype, it is a little on the lean side, but not horribly so. It's a musical amp overall, and that's what counts.

Questions -
1 - this was sold to me as a "SE" model, which I understood to mean that it was modified to allow the use of KT150's, which my amp has. Was this an 'official' factory modification, and if so, is the SE designation something which can be used when I try to resell the amp? I can't seem to find others running KT150's referring to their amp as the 'SE'. Or is the SE designation relating to a different upgrade altogether? 

2 - is this 'SE' amp backwards compatible with any other tube types?

2 - what's the next model up from the Ref 110 that might exhibit a little more tube bloom (warmth) than the  Ref 110? I wouldn't want to lose the wonderful transparency and soundstage ability of this unit, but if it could be fleshed out a little more then that would be a plus. The amp is only a couple weeks old, to me, so I'm still trying cables and supports etc, to see if there's more to be had, but I would say at this stage that this is a pretty amazing amp.

Any insights would be appreciated!


@cleeds - thanks for the suggestion and for checking out the arc website. I couldn’t find anything there either.

@erik_squires - thanks for that link! I’ve been googling but didn’t come across that particular thread. [EDITED - It seems to be conclusive on other ARC amps getting the 'SE' sticker and the KT150 seal of approval, but not my Ref 110. ]
I had a REF110 with KT120's.  I called ARC and asked if I could run KT150's and was told not it could not.  There never was a REF110SE.  I had a D115-mkII before the REF110 and a REF150SE after (and now want a 160S).  The REF150SE is definitely a better amp.  Thicker, more colorful and fleshed out, plus more detail that lets you hear deeper into the music.  Try to listen to one.
@docknow thank you, Sir, this is what I needed.
arc has took tube choice out of the hands of its customers unfortunately

you want this amp?  then buy this tube, only this tube, and oh, you buy it from me...  

too bad
Arc is sold by dealers who love the smell of their own farts. They are just overpriced traps.