I’ve noticed more than a few occasions where reviewers and owners mentioned the M1200’s tendency to somewhat emphasize the high frequencies and thought I share my experiences. Hopefully, other owners can chime in as well.
First, system context considerations. I’ve used the M1200’s with a number of preamps; a PS Audio BHK, Modwright LS36.5 and LS99, DeHavilland UltraVerve, and Luxman C700u. Speakers have been primarily second generation Tidal Audio Piano Ceras (ceramic tweeter, not the diamond model.) Also used the M1200s occasionally in another system with KEF R7 metas. The Tidal speakers readily reveal any downstream deficiencies.
Like others have mentioned, I initially noticed a tendency to seemingly highlight upper frequencies. As time has passed I suspect that perception is in large part the amplifier’s tendency to reveal any sort of electrical noise affecting the amplifier or source components rather than the amp itself suffering from any anomalies.
I say that because every thing I’ve done to reduce system EMI/RFI noise in turn smooths the amplifier’s tendency to highlight high frequencies in an unpleasant way. I use an Acoustic Revive Ultimate RPT-2 distributor to power the amplifiers and a Audio Mijinko distributor for the front end that uses the same basic concepts as the Acoustic Revive in construction. Those definitely lowered the system’s noise floor and smoothed the sound. Lining the home’s breaker box lid with Stillpoints ERS paper also had similar effects. The Audio Mijinko distributor is a two gang version of this four gang version on their website:
https://mijinko.jp/3673
I might also mention that the passive distributors sounded better in my system than did a PS Audio P3 regenerator, whether using the high power filtered or regenerated outlets.
The M1200 amps also respond more than my other amps to power cord changes. I’ve used a number of different cords and I’ve had good results with both expensive and inexpensive cords. Both Furutech PowerFlux and Wireworld Stratus sound excellent and balanced.
IsoAcoustic Orea footers also have had a positive effect and I prefer them to Stillpoints SS for these amps.
The last thing that continued lessening any tendency to unpleasant emphasis was perhaps the most surprising: installing Bybee iQse devices inside the M1200’s chassis over the ICE power module. I’d long been curious about those and when the Parts Connexion put them on sale last month I bought two. I tried installing them in two tube based preamps and they had no effect I could hear. Not too surprised because others had reported the same thing with their tube gear. They didn’t do anything more than the Stillpoints ERS paper did in the breaker box (another commonly mentioned place they’re used.) However, when I installed them in the M1200 amps, something was definitely happening. It took three or four days for the iQse devices to fully do what ever it is they are doing but the M1200’s have definitely acquired a rather less forward character without any tendency to lessen detail retrieval or otherwise suppress performance.
The M1200’s definitely still have their own unique sound with extremely fine clarity. Any sense of underlying grain or grit that made high frequencies in some recordings call attention to their presence has been greatly reduced to the point to takes a really bad recording to sound overly bright.
Some components seem to flourish with in multiple system contexts and with little tweaking. In my experience, the M1200s seem to reward careful system refinement and much of what one might think is the amp’s deficiency is actually just the amplifier telling you what’s off kilter downstream.