Hey guys, I just got M80's today and am floored. Great sound from these baby's. I love my Senn HD25's, but these are a different animal. As for "fun" factor, I'm finding these pretty damn fun. Absolutely great sound.
I will say that the Senn's seem to have a more "open" soundstage than the M80's at this point, but they're brand new and haven't been burned in yet. The M80's mids and upper range seem more bright than the Senn's.
I'm testing using classical, classic rock, 80's rock, and metal. To mix it up I'm throwing in electronic and alternative. As for the sound isolation...I use these for traveling on NYC subways to and from work...you sorta need to be able to hear when an announcement comes out, so I'm not against it.
I have noticed today that with these plugged into my iPod Touch, without my FiiO E17 that the battery drained faster than my usual IEM's....much faster.
More as they get burned in, but so far...wow...AMAZING little cans here!
Steve from NYC