Would like your tube amp recommendation

If you have 20.1, the no-brainer answer for tubes is ARC.

I use auto-formers with Maggies so it makes them easier to drive, but the big ARC amps will have no problem.

Frankly, to get what you want, I would go full ARC with the preamp and DAC too.  Go fully balanced to gain extra db and other advantages that will mate well with most ARC tube amps (some of which are strictly balanced).

Maggies and ARC electronics are ideal combo...but one other thing that expands the soundstage is...believe it or not...a great sub with Maggies.  A properly mated sub adds much more than just subterranean bass.  REL did a great demo at CES...Even with reference Rockport speakers, the subs added a level of ambiance and scale that recreated more of the recording space.

I don't know if they would drive your speakers, but you will not find a better tube amp than the Thrax Spartacus monoblocks.

Your best value and bet will be the 125 watt M-125 monobloc amps from tubes4hifi.  You can buy them assembled and ready to play for about $2800 plus shipping.  If you like to get your hands dirty, they'll also sell them to you as a kit for about $1800, minus tubes.

http://www.tubes4hifi.com/bob.htm#M125

I've been looking at a pair of PrimaLuna Prologue Premium monoblocks on AG for $2,800.  With KT120's they are 80W/ch.  Maybe bi-amping the Maggies is in order.  Keep the Accuphase for the bass, and PrimaLuna tube amps for midrange/treble.  Or maybe the PrimaLuna's alone will power the speakers.

I suggest you give serious consideration to the Octave MRE 220 monos.  I have them paired with my ARC Ref. 10.  I wrote a review on AudioShark that can be easily Googled.  In short, it is the best "of both-worlds" amp I have ever encountered: speed and precision of SS and the true-real of tubes.  Output: 220W/4ohms.  It can drive any speaker out of the box.  However, you can get an external power supply (Black Box or Super Black Box) to remove any doubt and to enhance soundstage effects.