Foster, welcome. Agree to skip the die-cast and bi-wire options. As to amplifier power, it depends on how loud of an average level you use and how much above that average level the peaks in the music you listen to are. 40 watts would allow for a peak level a little above 100dB at typical listening distances. This should be sufficient in most cases, especially if it's doing the job now(unless your present speakers are significantly more sensitive than the M60s).


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Enjoy the music, not the equipment.