Psi, just to say welcome and join the others in commenting that either of those units should have more than enough maximum power capacity for your M60s. Keep in mind that for an average comfortably loud level around 80dB the M60s will use a bit less than 1 watt. Low levels may use about a thousandth of a watt and brief peaks on some material having wide dynamic range(e.g., some recordings of some classical compositions)may have brief requirements as much as 20dB higher and could require as much as 100 watts, but that's still no problem.
