Hello Bob and welcome to the forum. I have owned the M3ti's for a while and have grown to fully appreciate their warmth, smoothness, transparency and overall balance. I have not heard the Polk or Def Tech monitors you mentioned but I can add the M3 V3 went up again a pair of B&W 805's in a blind listening test during Axiom's 30th earlier in September. Overall I do believe the M3's were voted better, but just slightly. Keep in mind the 805's are about $2500/pair. That should give some insight on how well the M3 can compete. At $348/pair it leaves a $452 for sub/center or maybe just a good sub (Outlaw, Hsu, Axiom) and Axiom's has a solid return policy. Only you can decide your preference after comparisons. Personally, I think the M3's are fantasic bookshelves.
