I think you will find every speaker in the Axiom lineup will outperform your BOSE cubes by a long ways. The BOSE cubes just can't give you the same soundstage as a true audiophile speaker, not matter what the brand.
THX really is just a badge, but if you want it go ahead. Any decent brand receiver from a reputible name like Yammy, Denon, HK, Onkyo, etc. will do just fine with most of the Axiom speakers.
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700