Wanting to try a tube amp.

@OP, 
I would also consider Atmasphere amps.
A quick check showed the ARC amps you are looking at are near $10K.
Considering your speakers are so efficient, I bet you'd get away with a lower powered amp. 
I own Atma MA-1's and they drive my slightly less efficient Vandy Treo's with ease.
And, dealing with Ralph Karsten is always pleasant. If you are interested, call him, he might have a demo available for a very reasonable price.
Bob

The VAC IQ series has balanced inputs, auto-bias as well as strong circuit protection.

I have a conrad johnson mv55 and it sounds amazing. It doesn't have balanced inputs, but that wasn't important to me and they can be had for about 1400 bucks. I build my own tube amps as well, but when I heard the mv55 I knew that I REALLY had to step up my diy game...lol

Its a good sounding amp playing through 94db speakers (audio nirvana super alnico 15" full range drivers in a ported bass reflex cabinet about as big as I am) and I never have to go past the 9 o'clock position on my preamp volume knob. Plenty of head room with enough to spare. I will never get rid of this amp. I absolutely love it.

I had a REF110 with a LS17se.  I was a great pairing and would be even better with a LS28se and give you a good taste of how great ARC tube amplification can be.  My REF110, purchased used, had been outfitted with KT120 tubes (it can not drive KT150s), and sounded great.  Highly recommended.