I use a m-50 to drive paradigm 3se speakers (6 ohm rated, 89db efficiency) without any problems. However I don't think
yamaha intended theamp to be used with 4 ohm rated speakers as there is only a A or B speakers switch . A+B would
be 4 ohms when driving 2 sets of 8 ohm speakers in parallel. Also the impedance of a speaker varies throughout the
frequency range. This amp is probably even more current limited than the m-40 or m-45 since yamaha did'nt
give a power rating for 4 ohms. If your speakers have to low of an impedance, hopefully the amp will go into protection.
The m amps are a great deal though.
