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Eastern Electric M520 Tube Hybrid Integrated Amplifier Review

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Audiophiles typically enjoy equipment showing up at their door, so it was the ultimate for me to have the M520 hand delivered by jovial Bill O’Connell, the U.S. distributor for Eastern Electric. When we learned that we lived relatively close to each other, Bill practically begged me to allow him to deliver the amp. How could I refuse? It certainly spoke volumes to me that Bill believes in customer service! Along with the amp came a compliment of tubes to roll. Bill had set up the amp with a tube compliment he enjoyed using with his Omega Superhemp speakers: (Front of amp to back) Mullard EF86’s first drivers, Amperex Holland 12AU7’s preamp splitters, EI Industrija Magnoval 6CA7 as the quad for push pull operation, and Phillips Miniwatt G234 rectifiers.

The sound was lovely, with midrange buoyancy, but being the bass lover that I am I longed for more emphasis in the bottom-end. My first exchange was to replace the EI quad for a set of JJ Electronic KT77’s. I was listening to Celine Dion’s A New Day has Come disc as a reference while I did each tube exchange. The KT77’s brought more weight to the bass and a touch cleaner treble. Celine sounded as though she had moved from a smaller venue to a larger hall, but not yet at the ballroom at Caesar’s Palace.

Next, I replaced the Mullard EF86’s with Siemens E80F’s, and put in the quad of Electro-Harmonix 6CA7’s.

Now things were getting good, and I could hear that Celine’s voice had aged. That may sound like an unusual term to use in describing the sound, yet that was the impression. I’m sure you’ve heard an artist rerecord a hit 15-20 years after their first recording. The voice matures, changes, deepens, opens up with the years. And yes, the venue sounded like Caesar’s Palace. This was the kind of change that was occurring with the M520 as I rolled tubes. I could literally determine if I wanted a young Celine or a more mature-sounding Celine singing.

Lifting veils to reveal more clarity through tube rolling can reveal more than you might want to hear! On Chris Botti’s Midnight Without You, vocalist Paul Buchanan, on the title track, “Midnight without You”, sounds so emotionally tortured that I felt like putting him out of his misery by swapping back to the original EI quads! At least with them it didn’t sound like he was having his trachea torn out!

Over time I was instinctively tuning the sound to move toward the sound of my bridged Pathos Classic One’s, a sound I’ve gravitated toward over the years, and with only two changes was I getting closer. I was amazed at how swiftly the Eastern Electric had morphed into an Italian integrated running as monoblocks! For the M520 at 25wpc (8 ohms) pentode to remind me of the Pathos amps generating 170wpc (8 ohms) was highly commendable! While there is a discernable difference in power between the two setups, the M520 carried more power into the performance than I expected from a sub $2,000 integrated.

After ample experimentation, I kept the amp on Pentode mode almost exclusively. Similarly, I returned time and again to the “Max” setting on the negative feedback switch. While on the “Min” setting, the presentation had a subdued bottom-end with sweetly blended mid/highs.

This presents a perfect option for those in close living quarters. On the “0” (zero) setting, the midrange exploded with air and the lower mid’s and mid-bass was emphasized. This made vocal duets enchanting. Every saxophone or piano became a center stage solo.


On the “Max” setting, the midrange moved back again and the strong, clean lower bass predominated, moving in the direction of a solid-state amp more so than the other two settings. This tri-fold effect reminds me of the fat pens I used in grade school, the ones with three separate color cartridges in one barrel – click whichever color desired and go with it. Similarly, choose the NFB setting you want and the M520 will oblige.

This is an amp that can accommodate many people with less than ideal system configurations. If you own a CDP that is detailed but a bit harsh, with the M520 you can tone it down. If your speakers are light on the bass, you can operate in “max” NFB to increase the damping on the woofers and improve it. Where there’s an audio ill, this amp can likely address it, if not perfectly then significantly. Before the M520, if some aspect of an amplifier’s sound is displeasing, the owner can do virtually nothing about it short of trading components. With a shape shifter like the M520, the possibility of redemption of the system is not just a hope but a reality.

Conversely, for those who are constantly shifting to different components in search of some elusive sound, they may find that an amp like the M520 will sate appetite for change. If they just have to keep changing things, they can change the output, the NFB setting, or tubes rather than change components constantly. That can save some serious change (or shall we say morph your budget?)!

At one point I thought I had pushed the envelope of the M520’s performance to its limits; but no, there was another surprise to come. And it came in the most unexpected way.

For many years I have been a firm believer in cleaning discs prior to play. When I get a new disc it’s cleaned even before first playing, since I’ve heard way too many times the not-at-all-subtle differences (and oh, what a glorious difference on a decent rig) between treated and untreated discs.

I have a lovely kit provided for review from Jena Labs, their Esoteric 3D-X disc enhancer (for CD/SACD/DVD). I thought I would test the enhancer while I had the Eastern Electric set up. It is difficult putting into words just how radically the M520’s sound morphed. I had been listening previously to a Dussun V8i, a 250Wpc-monster of an integrated, a brute with seemingly bottomless, abysmally deep bass. The poor M520 seemed a lightweight in comparison.

But then the 520 did it again, it morphed into a completely different amp. After one simple treatment, it sounded uncannily like the 250Wpc Dussun! Granted I never would have heard this formidable side of the Eastern Electric had I not experimented with the disc. I was all set to say the bass was respectable, not earthshaking, to cede the deep-end to the Dussun, etc. “Wow,” I thought, “I had better be careful with this component, it’s dangerously deceptive!”

Here’s an illustration in an attempt to explain how significant the changes can be with the M520. Recall, if you will, the laudable performance of Joaquin Phoenix as Johnny Cash in the biographical movie Walk the Line. If you were tuning in to the singing, he did a very commendable job as the man-in-black. It was only when the credits rolled and the real Mr. Cash sang that you hear the deep gravelly rumble of his voice. It’s quite a noticeable difference. It’s that kind of distinction in performance the M520 can pull out of its pocket.

When the M520 was first walked into my listening room, upon first listen I gauged it to be a respectable but middle-of-the-pack performer. With time, as I watched it morph into its many configurations, I heard it as an overachieving middleweight. Now that I’ve heard what appears at this point to be the outer limitations of it, I judge it to be exceptional.

I have put many dollars and many years into building an immensely satisfying sound from components that I culled after many A/B comparisons; and here in the space of several weeks, the M520 has gone from okay to outstanding! I have heard very few components that are capable of such fundamental improvements in sonic attributes as the M520. The truth of the matter, is that set up poorly, this amp will sound respectable. However, set up properly, with quality selection of tubes and utilizing premium cables, this amp can impress.

This is one reason why sometimes reviewers must give plenty of time with equipment. An hour or two will simply not do it justice. One must hear a piece over longer periods of time, with different tubes, with different speakers… and, of course, (as I heard) different CD treatments! But this opens up an entirely new can of worms…which CD treatment is the most exceptional? (See how we audiophiles drive ourselves crazy?)

With time, as my respect for this amp has grown, my caution in reviewing it also has grown. I do not want to misjudge it, to pronounce categorically it’s only capable of so much… because every time I’ve thought that, I’ve been proven wrong. When I didn’t feel there was enough “weight” to the performance of the amp, I kept moving the NFB switch until it showed up. When I wasn’t satisfied that “all the players were on the same field” spaced properly, I changed quads until they arrived. And on it went. When I felt it was cool in the midrange and voices were uninspiring, I put the Mullards in and vόla, there was the flesh on the bones! I’m sure if I could live with this amp for an additional year, I could find yet untold riches in it. For the record, the best configuration I have heard on my system to date was as follows: Mullard EF86’s, Siemens E80F’s, Electro-Harmonix 6CA7EH’s (two pair), and Phillips Miniwatt GZ34’s.

This has been one of the very few components which, since its arrival, had the effect of morphing me as a reviewer. It has altered my perceptions of what is capable at the sub-$2,000 price point. It has changed my dogmatism regarding how much bottom-end presence is possible from a tube 25-watt integrated. I adjure you, be very cautious in approaching this rare creature, it’s not what you think, it’s something else!

Associated Components:

  • Source: Rega Saturn cdp
  • DAC: Benchmark DAC1
  • Preamp: Melody Hi Fi P1688 tube pre; Dussun V8i ss pre stage
  • Amp: Melody Hi Fi S88 monoblocks
  • Integrated: Pathos Classic One MkII stereo tube hybrids (2) bridged; Eastern Electric M520 tube Hybrid; Dussun V8i solid state
  • Speakers: Chapman Audio Systems T-77; Von Schweikert Audio VR-4 SR MkII; Eminent Technology LFT-8A; Art and Audio Fusion Technologies “Picture Art System”
  • IC’s: MIT AVt MA; Jena Labs Java, Tice Audio IC 1A
  • Speaker Cables: MIT AVt MA; Jena Labs Jazz; Tice Audio 416
  • Power Cables: Xindak PF-Gold, Jena Labs Bumblebee
  • Power Conditioning: MIT Z-Stabilizer; Tice Audio Solo

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