Hi Dave,
I've been away on vacation and then extremely busy upon my return, so not much time for AC. I've been reading through this and find your experience to be interesting to say the least.
Your comparisons and descriptions seem to cove things as detail portayal, frequency balance, low level and high lllevel dynamics but you don't touch on soundstage, imaging, separation, nor harmonic, tonal, timbral accuracyand distortion atreference levels. When you get a chance could you provide your impression of the differences on these areas? Glad you've been enjoying this sojourn.
SoundGame: Because I am not a professional reviewer, a musician, or have any experience with or knowledge abut professional audio or speaker design and development. I am nor familiar with all the terms you have noted. But if you keep these critical caveats in mind, and with me looking up some of the terms, I will, as an amateur, and with apologies to those, like yourself, more knowledgeable than I, give it a try.
Soundstage: I think I have mentioned that I have been compelled to position to the M80s only five feet apart. This, naturally has narrowed the soundstage, which I don't find to be much of a problem. On the other hand, the M80s give the pleasant allusion that music is slightly extended beyond the edges of the soundstage, something I don't find with the MB2is.
Imaging, with Stereophile defines as "The measure of a system's ability to float stable and specific phantom images, reproducing the original sizes and locations of the instruments across the soundstage." I think I've written earlier, perhaps in my own terms, that the M80s are quite a bit better in pin-point definition of instruments across soundstage. Strangely, the M80s leave far less of the impression than the MB2is that music is coming out of a box.
Separation: If this refers to the directionality of the various sounds on the sondstage, I would say it is good on both speakers. The separation left and right is good, and to the degree that one gets the sense of instruments and voices being softer or louder as if they were nearer of farther from the listener, I would have to give the M80s the prize, by a margin, in this category. The closing bell on Pink Floyd's High Hopes fades and recedes better than on the MB2is, even though the soundstage is narrower.
Stereophile's glossary says timbre is "The recognizable characteristic sound "signature" of a musical instrument, by which it is possible to tell an oboe, for example, from a flute when both are sounding the same note." Again, I find the M80s superior in this regard. I have always found, depending on the player, that it can be difficult for me to detect the difference among soprano, alto and tenor saxophones when playing about the same notes. This is somewhat easier for me listening to the M80s than the MB2is.
The tonal quality, meaning the accuracy of the tone when comparing the reproduced to a live instrument, is hard for me to judge with any confidence since I very seldom listen to live instruments. But based on my shaky memory, I think the M80s do this quite a bit better than the MB2is. For example, with acoustic bass and tenor bass. I believe the M80s also have more accuracate tonal reproduction of piano decay as well as piano resonance.
I'm flummoxed when it comes to harmonic accuracy because I couldn't find an explanation that would define it in terms I understood. If you can help me out on this one, SoundGame, maybe I can attempt an answer.
Distortion at reference level is another term with which i'm not familiar. I did find this definition; "Reference level is the volume at 75db (decibels) in your room using full band pink noise. When you set up your system and you run pink noise through your speakers one at a time setting each level using an SPL meter to 75db you will (after all channels are done) and your volume control is set to 0db you will achieve "reference" when playing back movies or music. Movies will tend to reach peaks of 115db with your system set up properly."
This may not be what you had in mind, but if it means using pink noise, my answer is that I have not used pink noise on either speaker. In terms of decibel levels, I have only iPad apps with which to measure them in my room. I have listened for relatively short periods of time in the 80 db range, with peaking to the low 90s, without distortion that I could detect on either speaker.
I hope these comments are of help.
Dave