Linear Tube Audio (LTA) MicroZOTL Preamplifer

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LTA is a small company located in Takoma Park, MD., just outside Washinton DC. The heart of all LTA amplifiers is the the patented David Berning output transformerless ZOTL technology. Sonically, this delivers the best of both worlds: tube tone and solid state detail. Each unit is expertly built by hand in the United States.

I have followed Linear Tube Audio since their beginnings because of my association with Capital Audiofest. Mark Schneider started showing his products at the CAF2017 show. Mark joined our local audio club (DC Hi-Fi Group) and demoed at a few of our meetings. I have known David Berning a little longer since he is an active member and contributor to the out local DIY club (DCAudioDIY) and the DC Hi-Fi Group.

I was always impressed with the clarity, purity, and quickness of the LTA versions of David’s designs. There is a sense of great value in these products. When I decided to take the plunge and get a new system for this reviewing gig, LTA was first on my list to seriously check out. When I heard the new versions at Axpona 2019 I was blown away. The overall feel of the new LTA’s moved the needle a little more to my liking. I agree they are still very neutral but the leading edge of the notes seems a bit softer and rounder and far more holographic. I listened again at CAF2019 and the Florida Expo in February 2020. That is when I decided to pull the trigger and buy the LTA MicroZOTL for my reference preamplifier.

According to Mark, there were many changes in the new version of the MicrZOTL Pre. First, the obvious one is the new casework designed and built by Christopher Hildebrand of Fern&Roby. The new rounded edge chassis is the typical 17 inches wide, 4 inches tall, and 12 inches deep, weighing in at 14 pounds. Both the front and the rear bezel are a hefty 5/16 inch thick black anodized aluminum and the clamshell case is painted flat black. Going left to right across the front there is a power button, headphone jack, a 100 step rotary attenuator followed by a row of small white LEDs to indicate input selection followed by six brass capacitive touch buttons for control and finally, a 16 X 8 LED matrix info screen that defaults to the volume level. You can adjust the brightness of the LED’s or just turn it off completely. There is a remote control that handles most functions. There is a very understated elegance here. I love products that do not call attention to themselves. The fit and finish are superb. The hands-on experience is pure pleasure.  You do hear the relays clicking during volume adjustments and input switching. There is a lot of high tech going on inside just in the control circuit. This is where Mark’s work shines. This the first piece of equipment  I have owned that gives me simple pleasures in just using it.

The other changes are new PCB material and lots capacitor and resistor of changes, in types and values. No major changes to basic circuit design except the 100 step relay controlled attenuator, and an upgraded linear power supply.

A preamplifier is just one piece of the audio puzzle. It is the center of the system. It sets the stage of how all bits work and sound together. To me, it’s not enough to say it sounds neutral, not adding to or taking away from the music. That’s sophistry. The preamp is like everything else in your system, affects the sound. Does it add or does it subtract? I find that this preamp adds a unique character that increases my enjoyment of the music I’m listening to. I am now seduced, sucked right into the depths. I find no faults, only pluses.

The manual mentions that the preamp comes with 12SN7’s and can take 6SN7’s with a simple jumper change on the main circuit board. Since I had a pile of NOS 6SN7’s I popped in some NOS Sylvania’s. The difference is like going from table salt to the finest French sea salt. Everything just opens up a bit more. I then switched out the stock Phillips 12AT7 to some GE-0558’s. Again it was another level, the second Michelin star. I have never heard this far into the music in my system.

During my review of the Spatial Audio M3 Sapphire’s I used the LTA preamp exclusively pumping the time with the Eleckit TU-8600 300B SET amp. I have since built the Eleckit TU-8800 KT88 SET amp and have been listening to that amp for the past few weeks. The complete review of this amp will be coming up soon. I think this amp provides a couple more watts and is a better match to the Spatials.

I started the second round of listening tests with an old treat, Roger Waters, Amused to Death, “Amused to Death”. I know this recording is full of all kinds of audio tricks but I have never had the image of the low-level detail wrap so completely around me. The LTA is doing just what it is supposed to do, stay out of the way.

While I was in the “W’s” I ran across a Johnny Winter album, Guitar Slinger. I played a few tracks, but “Iodine in my coffee” and “Kiss tomorrow goodbye” are just fabulous.  Johnny’s solos are just show stoppers.  If you like the Blues this album should be on your shortlist. This digital conversion was not the best. I have the original vinyl and it’s much better.

One more deep dive into the “W’s” I found Suan Wong’s, Close to Me, the opening track “Vincent”, Susan magical voice just floated there before me in a holographic image, just marvelous. The music room just disappears into space.

An early Hilary Hahn recording of the “Gigue” from the Bach’s 3rd Partita provided a trip into the head of Johann Sabastian. This is a great recording and the LTA was up to its chops in delivering all the detail and nuances of Hilary’s Vuillaume violin.

I moved in my prized rebuilt Quad ESL’s for a listening session. I played William Ackerman’s  Sound of Wind Driven Rain. The transparency and quickness of the Quads were very evident through the LTA. This is a close-miked recording and the low-level detail shined through brilliantly.

Pushing the envelope and getting away from polite music I hit on Red Hot Chilli Peppers Blood Sugar Sex Magic, “Suck My Kiss” and Sir Phyco Sexy”. Maybe a better match for the Spatial’s and I am sure Peter Walker is rolling in the grave. But all the outrageousness is there in spades. Again the LTA just stayed out of the way.  Ouch I think my concrete floor now has some cracks

Back to reality and polite jazz, Joshua Redman Quartet live album Spirit of the Moment-Live at the Village Vanguard, “Jig-A-Jug”. The LTA  did not hold back any of the low-level nuances of the live recording hand the sense of the room was there, or I was transported to 7th Ave South.

Even though I am not a big headphone user I wanted to check out the headphone output. I asked Nicholas Tolson of LTA how the headphone output was derived. He quickly responded with….

“The headphone output uses the full circuitry of the preamplifier. There are no resistors or anything in the signal path…direct amp output, has the same output as the output jacks The preamp out has a 50-ohm resistor in the path to provide a load for the preamplifier, as it performs better with a load…”

I had on hand to review a pair of headphones that had their premiere at CAF 2019. The Aurorus Audio, “Borealis” are open-back headphones. They are a small company specializing in headphones. Founded in January of 2018, all of their products are assembled, tested, and hand-finished in the USA. Their goal is to create products that achieve the best sound quality with the best mix of materials and construction to create great-sounding, long-lasting audio products. I will be reviewing them soon.

This is the first high-end headphones I have had in my system. With a dedicated and well-isolated music room, I never saw the need to jump into the headphone realm. What I can say is that this combination of the LTA preamp and the Borealis is just near perfection. These are easy to drive headphones with a 32-ohm impedance. They are quite smooth and warm sounding. Maybe a bit heavy in the lower frequencies but just a bit. The treble frequencies are also properly balanced for me. The LTA preamp again is dead quiet and stays out of the way of the music.

I am just so pleased with everything about the LTA MicroZOTL preamplifier. The look and functionality all due to some very good engineering by LTA. David Berning designs have always been very clean and pure sounding. This combination is a winning one in my book. In today’s world with prices going into the stratosphere the performance of this preamp is a bargain at its price point of under $5k. I give it four and one-half stars.