Good timing, Mike!! I had the privilege of a nice long listen to the M156 monoblock tube amps over the last 3 weeks and have been working on a minim review. I rushed to press today to keep this thread sizzlin.
First impression, it sounds really good. They have great power, but a relaxed effortless presence. Tone is neutral and relaxed. Tone is natural and detailed. It seems more grown up than my Manley Snappers, easier maybe due to the extra headroom. After a few days I started noticing a pleasurable physical feeling in my gut that corresponded to crescendos in the music, chords and notes ebbing and flowing, and I can feel them inside me. Is it really physical? Or is it an emotional feeling from the solar plexus or navel chakra? Whatever, it was positive, it was palpable and it sure feels good. Bowed strings especially on rich thick chords like Respighi, Vaughn Williams or Brahms were enjoyable. A couple of late nights playing all kinds of music on the M156 amps followed, and I learned that it is very difficult to shut off, I kept on until my head was bobbing from exhaustion. Then again the next night, and the next. Was I addicted to this harmonic drug?
I could hear a touch of the 2nd harmonic and maybe third, that is much harder to hear individually. So it is not insignificant distortion % like a SS amp, but the feeling it generated was more than just 2nd, there is definitely some special recipe in these amps. Any lover of tube audio electronics should hear these - they are a classic just like the Minimax preamp. There is a little 2nd harmonic sunshine on top of solo notes, I can hear it slightly affecting the tone of acoustic instruments on classical recordings. Chords are slightly more plump than in real life, or is it juicy? Plump would imply fat and changed shape, but juicy implies same food but fresher, sweeter, more enjoyable. Bottom line, it is a very beautiful sounding amplifier, especially with so much power behind it to penetrate those harmonics into the body and really affect the emotions. I think most people, even hard core, straight and narrow, test bench spec audiophiles, would love the subtle harmonic embellishment which makes everything sound so beautiful.
Clarity and details are not sacrificed though, this is not the kind of tubey smeared slowness or rolled off highs typical of most tube amps posessing a dense harmonically enhanced so called 'magical' tone. It more like the modern Audio Research amps sound, very lovely in a magical sort of way, but probably a little more of love applied here than in AR Ref 110. With AR I can't hear anything specific, just feel it, albeit less intensely than M156. But with the M156 the feeling is palpable, it is not a subtle whiff of a rose 5 feet away like the ARC stuff - it is more like nose stuffed into a freshly bloomed gardenia. You get the warm and pleasurable feeling of SET syrupy tubes but without too much syrup. Details are easily audible, and aside from the sunshine, tonal accuracy is excellent. My first impression was that it was better than Snapper, more "conservative" without the snappiness of the Manleys. Most people will think tone is exquisite BECAUSE of the sunshine.
But "exquisite" and "accurate" are different things, as any mastering engineer or SS amp designer will readily attest. But listening in the home is for pleasure, after the mastering is finished, so let the technical and musical artistry of the disc be FULLY ENJOYED! Why hang a painting on the wall if the structure is just to keep you warm and dry? Because it is a HOME where love and life is experienced as intensely as humanly possible. Consider the M156 like a fine painting to be enjoyed for its contribution of beauty into the daily life.
After listening many hours to excellent recordings of classical orchestras, medium and small chamber music, some recent recordings on Naxos, EMI, BIS, etc I can attest that natural, honest texture and detail are all there, in the traditional standard of a high end audio amplifier. But with a spoonful of very special sauce on top that makes any musical dish even more enjoyable. But on pop and rock from Aretha Franklin to Alice in Chains, the tonal enhancement is irrelevant since the recordist and mastering artists use far more and far more indiscriminately than the subtle consistent effect of M156. The result is that any popular contemporary music was a pure pleasure, devoid of any audiophile nit picks!! Bass control on rock was awesome, relaxed and controlled, while still tinged with that luscious harmonic drug. Guitar and vocals whether smooth female or rough male were awesome.
I also love the power it makes, that is clearly noticable compared to Manley Snapper (100W) which sounds a little anxious like a race horse but otherwise very clear. Like all tube amps, the Snappers have some, but not as much, "harmonic enhancement" as M156, so details are slightly clearer, but the joy from them comes more from listening to the music itself. Bass on M156 is the most forceful and well controlled of any tube amp I have heard - this is 160 watts afterall, as monoblocks, with taps at 4, 8, and 16 ohms to match the speakers appetite. I used 8ohm tap with the Usher Be20. I found the Snappers to still be overall a little snappier in the dynamics, which is one reason I love them so much. M156 was plenty dynamic especially macro dynamics which are easier to notice. I often questioned my own opinion that the Snappers were snappier, especially on big crescendos and such. But the added power of M156 made big moments much bigger than the Manleys.
With the stock EE driver tubes the harmonic enhancement was more restrained compared to the set of vintage Brimar input tubes provided by Bill O'Connell for a little tube swappin fun. The Brimars are a little on the tubey side for me, but very pleasant. But with the stock EE tubes installed the amp stood up straight and came to life. The overall performance improved so much that I had to wonder whether the stock EE 12AU7s might have the same transformative effect on my own EE Minimax preamp. I had never even tried the stock signal tubes, as I suspect is the case with many minimax owners who buy the pre for the swappin good times, and so sure that the stockers must suck, just relegate the stockers to the cozy poly foam packing materials from which they came, just like I did. But inspired by the experience with the M156, sticking the EE 12AU7s into the minimax proved to be a major advancement for my system overall. With either amp, Manley Snapper or M156, the stock preamp tubes took the system to a new level that I thought I would need a much more expensive preamp to accomplish. Delicacy, immediacy, and amazing clarity and tonal precision from top to bottom are astouding, comparable to other great tube preamps that have come to visit my system on loan, like SAS 11A, ARC Ref1, and Cary SLP05. Anyway, the mini combined with the M156 both using stock EE 12AU7 signal tubes made an awesome and delightful combination. All that exquisite harmonic loveliness of the M156 was retained while the EE branded input/driver tubes added more clarity.
I don't know if EE designer Alex Yeung has voiced the M156 deliberately to be slightly euphonic, or if it is inherent to the Chinese new production copies of Telefunken EL156 power tubes, but the joyful beauty and relaxed power are the two most noticable characteristics in the listening. It is very easy to love and hard to shut it off, very addictive.
The amps are gone now for a photo shoot, but I look forward to hearing them again, in different room, on different speakers, different preamps. Thanks Bill, for the opportunity to sample Morningstar's latest creation up close. Great fun!
Rich
