Monk I think M60 would satisfy your needs as my listening/livingroom is also 20 x15. Got back into hifi last year with a rotel cd player and amp. Had problem with M60 brightness. The cause is not Axiom speakers it is the SOURCE, despite contrary opinions on this site. Upgraded to Mark Levinson #39 cd player solved brightness. Although my M60s are most modest part of my system and are derided by my so called audio 'friends' as mid fi AV speakers, I personally love them. Also recommend classe products as your amp. I picked up classe CA-100 for $800 US. All components bought pre-owned, mostly on Audiogon, except Axioms:

Mark Levinson #39 cd player "run direct"
Classe CA-100 Amplifier
Harmonic Technologies Pro Silway XLR interconnect
and PRO AC power cords
Nordost Red Dawn bi-wire
Axiom Millenium M60ti
Behringer Ultramatch and portable Sharp MT-877 minidisc for portable music

Enjoy the Music !