This review page is supported in part by the sponsor whose ad is displayed above
Don't believe everything you're thinking.
I've met Bill O'Connell from MorningStar Audio only once. That was two years ago at the CES during a 10-minute blitz through the exhibit he shared with the two bald guys from Portland's eponymous audio outfit. However, many MiniMax owners who've trusted my reviews have since reported back by e-mail or phone. I've thus come to know Bill somewhat vicariously and second-hand: by how they gush over his service; by how happy they are not just with their acquisitions but with knowing that a real gentleman with old-fashioned notions about customer support stands behind 'em and happily accommodates them with all manner of trial tubes if they want to roll. "Just send back the ones that didn't work out for you" apparently accompanies a dozen tubes on a routine basis. It was hence with significant trepidation that I called Bill. You hate to bring bad news to good people. Alas, I had to report that his M520 just wasn't cutting the mustard.
As I already stated in my Abby/Bailey review, the half-priced Onix SP3 demolished the Eastern Electric piece in overall control, bass articulation, image specificity, focus, resolution and drive. By comparison, the Mullard circuit sounded removed and somewhat indistinct, bloomy, liquid and wet but also way woolly and not in control of the transducers. In fact, it sounded like a serious lack of damping factor. To boot, where the Onix was quiet as a shy church mouse into the 95dB Abbys, the M520 sounded like a faulty air valve. I could hear hum through the speakers from 15 feet away. It didn't sound like a ground loop, it sounded like grunge from a poorly regulated power supply.

Now add the 8/16-ohm taps and the specific recommendation to connect 8-ohm speakers to the 16-ohm terminals. Aha. No damping factor. That explained it. This didn't make me feel any better about the prospect of finally penning the 'obligatory' scathing review but at least I felt vindicated.

Then a package of new tubes arrived from the MorningStar man. I dutifully inserted most of them to note some improvements but nothing significant enough to turn the tide. Except that Bill had also included a tube labeled Philips E80F. It was significantly taller than the mesh plate E86F Sovtek which was the only stock small-signal tube left to replace after I had swapped the rectifier and 12AU7. I was sure Bill had sent the wrong tube and didn't insert it for fear I'd damage the amp. When I confirmed receipt of the tubes, Bill implored me to try the E80Fs. So I did. "What the..."? Total and utter transformation. More about this anon. It got better. One of Bill's customers with hi-eff Lowthers had noise problems similar to mine and magically banished them by lifting the amp's ground. I was skeptical. I can tell (I think) the difference between a ground loop, an open interconnect ground and power supply ripple. But I did lift the ground just to benefit the
doubt. What marginal speaker noise remained after I had pulled out the bad weed of a Russian E86F dropped to utter insignificance. Now I was home-free to report on the M520 performing as intended. The amp now positively dared me to think evil thoughts about design flaws, head-first full frontal nudity plunges into empty swimming pools, missing damping factors and surfin' power supplies. Moral of the story? Don't believe all of your own thoughts. And while the designer readily confesses that his 16-ohm connection is unconventional, it was arrived at after much listening and in all instances sounded better to the listening panel. Those with 4-ohm speakers insisting they need a 4-ohm tap can be accommodated by special order.

The upshot of my E86F experience? No US samples of M520s -- in fact, no Eastern Electric product for American customers -- will be shipped with any Russian tubes again. My review sample was the first amp in the country and O'Connell already has taken receipt of 140 of the E80F Philips that rectified my issue. More are enroute while Alex is scouring global supplies for properly spec'd EF86s. Accordingly, nobody else should experience what happens when the preamp stage of the M520 is fundamentally crippled by a noisy and out-of-spec valve.

As noted on the Abbys and more vital even on my Avantgardes, the taper of the motor-driven attenuator is presently too steep - by 9:00 at the latest, you've maxed out your ears' headroom on 95dB speakers, never mind 103dB variants. When speaking to Alex Yeung a second time, I learned that he hadn't really anticipated high-efficiency speakers being hooked up to his 24wpc amplifier. He's now planning to make the necessary adjustments on the pot's gain structure to accommodate such scenarios. The PP/UL mode switch (front-panel and remote actuated) generates an insignificant and completely benign mini transient when engaged. It's a night'n'day difference from the enormous mechanical clunk and electronic whammy Manley's single-ended/push-pull switchable NeoClassic monos prompted during their review. The switchable mode feature here is a real doozy. It not only affects output levels (pentode is louder) but, of course, sonics.

On all speakers I tested, I preferred pentode for being gutsier, more fleshed out and saturated than ultralinear. Ditto for feedback. Once I had gotten over the initial false impressions caused by the Sovtek preamp bottle and the subsequent brain cramps it invited -- over missing damping factors and unusually high output impedances which would invite adding copious amounts of feedback -- I had to agree with the designer that his central NFB position also sounded best to me: a bit looser but also freer, with higher amounts of feedback drying things up. With 12 different flavors on tap (3 feedback x 2 mode x 2 output taps), I flashed fondly on the Mesa Baron and Tigris which offered similar morphability.

Increased feedback and matched output impedance (i.e. 8-ohm speakers like my Gallos into the 8-ohm tap) did benefit especially bass grip and control but I ultimately was happier sacrificing a bit of low-end crunch -- relatively speaking; this is no Krell -- for flow and saturation and opted to go 16. Usually, the term saturation is reserved for the octave-doubled euphony of single-ended amps since it mimics over-developed color temperatures. That's not what the M520 does. But this amp is clearly all about tone, just in a different fashion. For one, it operates all across the board rather than fixating on the vocal range. For two, it's neither ethereal nor glowing from within. This is a full-bodied, slightly soft sounding amplifier that's modestly lush but not at the expense of moxy and rowdiness when the material calls for it. No deep triode here though an intrinsic sense of relaxation does paint parallels. This differs from the Onix/Melody SP3 which acts more muscular and virile, tauter and a bit cooler.

I never thought the M520 was in the least ponderous. However, it was warm and slightly fuzzy around the edges. It easily drove the Ref3s to deafening levels, with the bass not exactly plump but definitely not lean and chiseled either. Call it shapely. Unlike some older Cary 2A3 monos I spent some time with quite a few years ago (and which have long since been discontinued), the Eastern Electric integrated didn't suggest old-timey vibes in the way those seriously golden-hued black-and-white photographs of the old West do. Neither did it strike me as a blatant throwback into the past in that exaggerated fashion most of us not deeply familiar with the genre think of vintage amps (especially those that likely suffer out-of-spec worn parts). The M520 really is what it is - a modern interpretation of an old circuit with present-day parts and certain tweaks. The 'old' half of this recipe is a certain comfort sound that's about tone and timbre and beauty. The 'modern' part pays obeisance to current notions of resolution. Alex Yeung's genius is in how well he has balanced out those two poles. My pre-E80F experience was the caricature of deep vintage valve: warm, wet, woolly and out of control. Once the preamp stage operated with the proper valve, control kicked in but the flavor of warm and wet remained. The woolly part simply coalesced and gathered itself but never shifted into overtly incisive or assertive.

This naturally means that the M520 isn't a resolution monster per se especially in the settings that maximize its own potent charms. The non-adjustable 5881 Onix piece with the mysterious extra tube (nobody seems to know what exactly the third small-signal valve is doing) is more resolved and transparent, grippier all around and more extended in either direction. The flip side? It lacks that fullness of tone, that peculiar non-S.E.T. saturation the Eastern Electric amp possesses in spades. I assume that a Unison Research or Shindo-type push/pull pentode amp would retain that tone and general gestalt but raise the ante in the resolution stakes - for a significant increase in expense. Depending on your priorities, the M520 could be your perfect entry into this milieu. It begins by celebrating the contents of each tone before it addresses ultimate transparency to separate out the 7th second violin player from the 8th in the mass of a big symphony. How would adding the MiniMax preamp maximize, alter or dilute things?

Upon power-off and subsequent power-on, the M520 defaults to the left-most input on its display - CD. If you were listening to another input before you shut down the amp, you need to reselect it now. This goes for the pre-in feature as well. You do have continuity - you're simply on the wrong input until you reissue the command either by remote or on the front panel. This is the only functional oddity one might wish addressed - that the amp remembered the last-used input whenever you turn it on. As Alex had explained, the M520's active preamp stage represented by the E80F "morphs" into a driver stage in pre-in mode. That dumps significant gain in the process to allow the preamp to add its own gain to the chain. Works like a charm, too - no noise issues even with a hi-gain preamp like the MiniMax whose attenuator would be at 10:30 o'clock to equal the M520's own at slightly lower than 9:00, thus giving me a wider range of control options.

Don't believe everything I am thinking.
With my MiniMax set to slightly lean and transparent rather than lush and opulent (simply a function of what valves you use), I was pleased to hear that this transferred just as expected, shifting the sound of the Eastern Electric pre/power duo more into the Onix SP3 camp while retaining that famous bluesy tone of the EL34s. I got more ambience and air and an overall lighter feel. This enhanced transparency was particularly welcome at truly low listening levels such as you'd use when your beloved is already asleep in the next room separated merely by an archway curtain. Hmm. This MiniMax/M520 combo really did it for me. The flexibility options of the M520 had just exploded into "multiply this by infinity and you'll still have barely a glimpse of what I'm talking about" (Brad Pitt as vacationing Death in Joe Black explaining his job's complexity to Anthony Hopkins). This turns our integrated into the proverbial Swiss army knife. It of course also means that the exact sound you can achieve is a matter of the available adjustments plus the variables of tube rolling. All my review can thus hope to accomplish -- even more so than usual -- is to paint a general picture as I've done above. The details and permutations remain for you to explore.

Seasonal moods.
Audio comes for all seasons and the M520 is clearly an autumn component. Temperatures are still warm but not as excessive as in the summer. The hues of turning foliage is an intense color spectacle, the quality of the light not as white and brilliant as in July. Contrasts are a bit softer and for many people -- outside of May when spring's here to stay -- Fall is the richest and most romantic season of the year. The mood becomes somewhat more languid, as though in anticipation of Winter's hibernation when people consume heavier foods to fend off the cold. Autumn is thus the season in which the M520 roams. What month exactly will depend on how you voice it.

Wrapping up, Alex Yeung's design brief -- to reintroduce a famous circuit of audio antiquity in a contemporary makeover and with certain circuit lifts -- appears to have manifested to perfection. Remote creature comforts placate the modern beast while sonic comforts harken back to slower times yet don't induce a complete time lapse that today's contemporaries could no longer relate to. The pricing takes advantage of Yeung's proximity to China while his sonic sensibilities only entrusted Japan to supply the vital transformer cores. MorningStar Audio elected to sell consumer-direct in the United States to control the final retail and offer hands-on interactions between supplier and end user. Build quality and cosmetics are what we have come to expect from this firm, which is to say flawless and expertly executed. And while my encounter with the M520 started off on the wrong foot, I'm pleased to report that a simple replacement for the originally supplied preamp tube eradicated any doubts I might have harbored that Alex Yeung's winning streak had mysteriously come to an end. Not at all.

It continues unbroken with yet another example of a true value product that's intelligently packaged with just the right -- and some unexpected -- features. My hat's off to the golden ears in Hong Kong. Not only haven't they tarnished, some of that gold color has clearly rubbed off on the M520's sound. It's not the flashy glitz sheen of ostentatious street jewelry or the brilliance of white gold but the far more subdued and classy hue of copperish red-gold. That makes the M520 into a full-on tone monster. Once you hear it, you question the sanity of many modern components that have turned their collective backs on this particular strength of vintage valve amps. Thankfully, the M520 rekindles this flame. You don't have to consider refurbishing antiques since afterwards, you might still conclude that for all their charms, those simply are old-fashioned and no longer appropriate when surrounded by modern high-resolution gear. This amp doesn't suffer those limitations. And that, precisely, is its special appeal and achievement...
Manufacturer's website