Actually, in the case of the M80 any amplifier capable of driving a 4ohm load will be fine. Unlike many 4ohm rated loudspeakers in the industry, the M80 is REALLY 4ohms when spec'd according to the IEC standard (IEC/EN 60268-5).
Andrew
You should consider getting a separate amplifier that can handle down 2-4 ohm loads if you choose either the M80 or the PSB sync one. The PSB synchrony one impedance graph dip very low and might be a little too much for some electronics. While I don't have any experience with this speaker you should ask your dealer if people do power these with receivers or if he gets any complaints of them shutting down any electronics. They are still pretty efficient which is a bonus and I imagine they are an excellent speaker.
