Birdman, although it's been pointed out several times here that the Crown calculator gives a result far too high for home listening rooms, it continues to be cited occasionally. Crown is primarily a pro amp manufacturer and the calculator is designed for use in relation to open spaces rather than enclosed rooms. This fact isn't indicated in the calculator screen but only in a separate discussion
here and only rather less than prominently under "Other Considerations". They suggest a 6dB correction for use in enclosed rooms rather than anechoic outdoor venues. Without this 6dB correction the calculator result is 4 times too high.
You don't mention the key factor, listening distance, but at a typical 10 feet, your M60s use about 1 watt for a 85dB sound level. 75 watts would supply a peak of about 103dB.
