72(a good rule to know, indeed)another welcome. There's no need to be concerned about your 540 "matching" speakers. If it was an extremely low-powered unit, special attention would be given to getting speakers with well above average sensitivity, but the 540 has enough power for speakers of typical sensitivity(such as the Axioms)in typical rooms playing at typical levels. You don't mention a sub, and the M60s would be an excellent choice for your room size, with more bass than a bookshelf. I'll also comment however, that my M22s provide adequate bass for most types of music(no pipe organ allowed)even when used without a sub.
