Those who have been following this topic since I posted my review of the M80s will have seen that I have compared them very favourably to my PMC MB2is. I have now listened to them for, I guess, more than 100 hours, and that opinion only has been reinforced. Growing accustomed to their sound, I prefer the M80s' high end and the bass; the high end is brighter than the MB2is, the way I like it, and the bass is tighter and more defined. The imaging is distinctly better IMO. I say this recognizing that the PMCs are terrific. I am certain that others do, and would prefer, their sound.
And now I have little doubt that M80s are "uber-revealing" compared to any speaker I've had, including the MB2is. But that quality, as is well-known, is double-edged. Good recordings sound better, but bad ones can sound awful. And I'm finding that a lot of recordings I formerly thought were good, aren't so good, and in certain passages, are very bad indeed.
In particular, on some recordings, on some passages, I have been hearing a kind of rasping, new to my ear, that until yesterday, I worried might be distortion caused by the M80s. It happens with some voices, some piano passages played in the upper registers, some sax, and some combination of instruments. The sound is unpleasant to my ear.
Yesterday, I tried these same recordings and passages on my MB2is, but this time at higher volumes, knowing that these speakers need to be cranked up to get them to work best. And there it was - the rasping sound, which I hadn't noticed before when I had listened to the MB2is at less than very high volume, which is my usual practice. Conclusion: the recordings are at fault, and the M80s don't need to be cranked up to produce it.
Readers of this topic also will have noticed that I have been a little shaken at the prospect of confronting the possibility that I might prefer the Axiom sound to the PMC sound, which in my case cost me many times more than the price of the M80s. I've asked, "Then what?"
The eventual decision, if I have to make it, could be a big one. Keep both, sell the MB2is, something else. Or, I might just get used to it; indeed, I probably will over time. But like Scarlett O'Hara, I'm going to think about a big decision "tomorrow."
Still, the occasional rasping, the byproduct of the M80s' extraordinarily faithful reproduction, is not pleasant to my ear. I am waiting to receive Axiom's DSP designed to improve the performance of the M80s, which should come to me in the next several weeks. It may soften the rasp or make it worse; can't know for sure now.
In the interim, I want the choice of addressing that rasp until the DSP comes. My Bryston preamp, like really good ones, has no tone controls. My lesser device, the Harmon Kardon (HK) receiver has old fashioned tone controls, and I've found that dialing back the treble softens the rasp, which helps me get past the recordings and passages I now find difficult. But as Axiom has made clear to me, although receivers do a good job with the M80s, they cannot bring the best out these speakers the way my Bryston would amps would.
So, as an interim step, I have decided for the next several weeks to use my big 7BSST2s and, at the same time, have access to the HK's treble control. Therefore, I've detached my MB2is from the 7BSST2s - "The horror, the horror" - it felt a bit like taking them off life support. I've hooked up the M80s to the 7BSST2s, and I've used the HK pre-out to connect the receiver to the 7BSST2s, which allows me to use the HK treble control when I need it.
Not the ultimate solution. But one I can live with for the moment. The solution, if I can decide on one, thankfully, I can think about tomorrow.
Dave