saunig
The M80s are efficient. Efficiency is usually expressed as the sound volume in decibels measured at a distance of 1 meter from the speaker with 1 watt of power into the speaker. A speaker with 93 db efficiency will output 93 dbs (really loud) at 1 meter with an output of 1 watt from the amp into the speaker.
If you are sitting 3 meters from the speaker, the sound pressure level falls inversely proportional to the distance 1/r from the sound source. (Not the square of the distance!)
Therefore, if the output is really loud (93db) at one meter, it will still be plenty loud at 3 meters.
Now, Club Neon's concern about clipping with tube amps is misplaced. Tube amps clip softly. That will not damage your speakers.
That having been said, the M80s have twin tweeters and are rated at 4 ohm average resistance.
I would go with an integrated tube amp. There are many high current and high output tube amps which are notorious for their beautiful sound quality and ability to drive difficult loads:
Antique Sound Labs Hurricane, rated best amp by The Absolute Sound a few years ago. The Prima Luna Mystere amp should do a wonderful job with far fewer watts. 25-50 wpc should be sufficient to push M80s to very loud sound levels.
Pacific Creek makes some very nice tube amps, JoLida (great amps), Manley Labs (check out their Stingray). I'd check out the H.H. Scott vintage amps modified and upgraded by Mapleshade Audio (Pierre Sprey's outfit), I would also consider the Vincent hybrid tube/solid state amps. [I may pick one of these Vincents up soon]
Any of these 50 wpc tube amps should drive the M80s to high sound levels and provide you with the audio bliss of a good tube amp coupled with a pair of great speakers.
BTW, there are many tube amp manufacturers in China which are putting out excellent tube amps.
