DD, quality speakers such as your M80s can't be blown simply by playing them too loudly. Your ears would give out well before the speakers would. What could possibly happen would be damage resulting from the amplifier clipping if it couldn't supply the power needed.
Looking at your hardware, it clearly is capable of sound levels beyond what's safe to your hearing. If you're speaking of a movie at -8dB, if your setup is correctly calibrated that equates to about 97dB(the max peak in a movie channel is 105dB). This peak would require about 20 watts for the M80, so louder would be possible, but most listeners, including me, consider that to be loud enough for home listening.
