Gramophone Dreams #36: Linear Tube Audio Z10e integrated amplifier

I hope you can tell how grateful I am to be writing a column every month. A column makes me feel like a reporter or raconteur, both of which I aspire to become. In a column, I can be more me. I can evolve, think out loud, and speculate, right in front of you. I can pass on crazy stories from a lifetime of audio. When I write about products in a Dream, I try not to form it as a review, per se, but rather as an informal chronicle of discovery.

This month's chronicle is about a unique product I've been anxious to explore since I encountered it at last year's Capital Audiofest: Linear Tube Audio's all-tube Z10e integrated amplifier/headphone amplifier/electrostatic headphone amplifier ($6950, footnote 1).

Like the LTA Z10 integrated amplifier from which it morphed, the Z10e is built around a David Berning–designed push-pull output-transformer-less (OTL) EL84 tube power amplifier that is rated at 10Wpc/8 ohms and 12Wpc/4 ohms. Whereas LTA's regular Z10 is a genuine full-function tube integrated amplifier with five line-level inputs, a tape monitor loop, and ¼" front-panel headphone outputs, the Z10e is a distilled, shape-shifted version of the Z10, designed to appeal to today's new breed of headphone collector-connoisseurs.

The Z10e retains the Z10's HI- and LO-power headphone outputs but has only three line-level inputs and no tape loop. It adds a five-pin, 580V-energized Stax electrostatic headphone output—hence the "e" designation. That's a huge deal.


"A single component solution," says the LTA website, "the Z10e incorporates the acclaimed ZOTL10 power amplifier, a Berning-designed preamplifier, and the LTA control system with three inputs [one balanced XLR, two single-ended RCA]—all packaged in a beautiful aluminum low-resonance case designed by [Virginia-based audio company] Fern & Roby." The Z10e case is beautiful not only because of its subtle brown- black color and the superb quality of its finish; its aesthetic essence lies in the just-rightness of its Parthenon-like proportions: 12.75" wide × 6.5" high × 14.5" deep When I reviewed Linear Tube Audio's first product, the microZOTL2.0 line stage/headphone amplifier, I was equally impressed with its classic proportions.

Like the Z10, the Z10e has a tube complement consisting of two 12AT7s, four 12AU7s, and four very cool-running EL84 output tubes. The Z10e connects via a soft, extremely flexible, removable umbilical cord to a separate, perforated-steel power-supply box that measures 4.75" × 7.5" × 4.25."

With the DeVore Fidelity O/93s
We all know it is impossible to audition an audio component without inserting it into a functioning audio system. Hence, it's impossible to completely separate my observations about a component from the sound character of the system. Correct?

Therefore . . .

It is inevitable that occasionally I will stumble on a complete system that grabs my attention and says, "Whoa! This system really rocks some musical magic." By accident, I discovered such a system only hours after inserting the Z10e in my floor system.

It isn't free or cheap, but this system is simple and exotic—and it played the dancing devil out of every recording I threw at it. If your taste is even vaguely similar to mine, it could be the last system you will ever need. Why? Because it's old-school (no class-D, wireless, or DSP) and straightforward, and it consistently triggered live-music feelings in my brain. Tonal accuracy earned five stars, 10 times out of 10. Wood/metal/strings/electricity/reverb/piano/human voices all sounded correct. It played headphones with an equal level of authoritative realism.

This play-forever system was built around the successful partnering of the LTA Z10e integrated amp and the $8400/pair DeVore Fidelity O/93 loudspeakers. The O/93s are rated at 93dB/W/m and have a nominal 10 ohm impedance. You must choose your own sources, but for this report I used the Chord Qutest DAC, which keeps making me happier and happier. And of course I used a record player: the Dr. Feickert Blackbird with a 12" Jelco TK-850L tonearm and a Koetsu Rosewood Signature Platinum moving-coil cartridge.

This system played slightly warm and was unabashedly dynamic. Its rhythmic drive could burn rubber and pull trains. Think: lively and tactile with supersaturated tone. Helping to achieve this enjoyable balance was AMG's Reference tonearm cable (because of its powerful wow'n'jump factor) and the nearly invisible Triode Wire Labs Spirit interconnects between the EMIA Phono step-up transformer ($2400 with copper wire) and the Tavish Design Adagio phono stage ($1490). I used Black Cat Coppertone interconnects from the DAC to the Z10e, plus the not-warm/not-cool Triode Wire Labs American Series loudspeaker cables. Digital (USB) cable was Cardas Clear HS.

After putting this system together, its extraordinary tone character forced me to binge on Terry Allen and the Panhandle Mystery Band. The first Allen album I played was Pedal Steal + Four Corners (16/44.1 FLAC Paradise of Bachelors/Tidal). The first song I played was "Pedal Steal: Chapter 1": "He played steel guitar / And the drugs broke his brain off at angles / But his fingers played true to his heart." And I cried. Because of the poetry of the concepts, and because the tones of everything in this Terry Allen sound collage were reproduced completely. There was a distinct feeling of wholeness to the musical presentations. My mind saw the inside of Allen's mind.

In my world, if the tones of everything are not accurately reproduced, the audio system is defective and useless. If the poetry of concepts is not fully exposed, important musical information has been lost—and so has my engagement. I've experienced countless audio components that measured well, but only a rare few that produced authentic tone, nine octaves of natural detail, and copious atmospherics. The LTA Z10e driving the DeVore Orangutan O/93s did all that.

With the Zu Audio Soul Supremes
I'd forgotten how much I enjoy the dynamic ease and sheer directness of Zu Audio's Soul Supreme loudspeakers. Zu Audio specs the Soul Supremes at 97dB/2.83V/m, and they have a nominal 16 ohm impedance. Their 10" paper-cone crossoverless full-range drivers (and ribbon tweeter) lifted layers of veils from the sounds of familiar recordings. They were the most unveiled between 50Hz and 800Hz. The high sensitivity of the Zu speakers untethered the LTA Z10e. It flew. With the Zu, the LTA's modest power cast no shadow of dullness over dynamic, bass-heavy recordings. Bass detail appeared with tube beauty and solid-state force. Ten watts seemed plenty.

After twice watching Robert Eggers' second film, The Lighthouse, I became obsessed with Aran sweaters, mermaids, and drunk men dancing. I fell also into the dark waters of that film's Mark Korven soundtrack (24/96 FLAC Milan/Qobuz). I never thought I'd experience bass of that quality in my room—and from a 10Wpc OTL tube amp, no less! Dense, detailed electronic textures, pulsing low-frequency forces, and infinitely dark spaces presented over an eerie ebbing and flowing of time: Those are the elements that made listening to "Murder/Mermaid/ Heavy Labour" (from The Lighthouse soundtrack) into an expansive, emotionally charged night vision. Unforgettable.

I was aiming for delicacy and atmospherics when I chose this system's Cardas Clear HS USB cable (because it resolves atmospheric info very well) and Black Cat Coppertone interconnects (for their exceptional transparency). For the same reason, I chose Cardas Cygnus loudspeaker cables (because they are slightly warm and, like the Cardas USB cable, recover space and atmosphere extremely well). What I heard from this system surprised and delighted me—especially the sheer mass and volume of deep, energized space.

Footnote 1: Linear Tube Audio, 7316 Carroll Ave., Takoma Park, MD 20912. Tel: (301) 448-1534. Web

Bogolu Haranath's picture

HR could also review the Linear Tube Audio ZOTL 40 reference amp (with measurements, please), $6,800 :-) ......

nicholas_lta's picture

This is Nicholas from LTA. I am including below the manufacturer's comment we submitted that appears in the back of the print edition of this issue. This clears up the issue of the power of the regular headphone output.


[Note: this Manufacturer's Comment has been added to the main article as a sidebar]

er1c's picture

Your sentence; "if the tones of everything are not accurately reproduced, the audio system is defective and useless" is confusing. I feel some vague kind of loss. Warmest regards anyway. Walks away head down.

MhtLion's picture

For the price of Z10e, I wish it had a balanced headphone out. No matter what anybody says in terms of inherent single-ended design, no advantage of balanced, etc. All that may be true from the product engineer perspective. But, Single-Ended headphone cable is fundamentally wrong. Just who with the right mind will want to spend north of 10k (DAC, AMP, Headphone) and decided to short the return cable path? Would you ever do that with your speakers? Will you short the return cable of your speakers for any reason? Some of these headphones use just as much as electrical current as the efficient speakers. It's just an insanely fundamental design flaw. It does not matter an amp is SE or not, all the headphone out should switch to XLR type, just so it does not short the return path anymore. On average, there is over 20 dB difference in crosstalk alone when you stop shorting the cables. Your 6k amp may be perfectly engineered with SE design, but for the users - it's a very different story.

headinclouds's picture

Like you Herb I really enjoy music through the LTA Z10e. I have owned mine for seven months now and it is a great component. It drives loudspeakers very well and the quality is maintained at high and low frequencies. As you say “I never thought I'd experience bass of that quality in my room—and from a 10Wpc OTL tube amp, no less!”
It is important to distinguish OTL from the circuit invented by David Berning which is ZOTL.
Most conventional attempts to eliminate the output transformer have the tubes driving the load directly. They have problems with low loads and need lots of tubes in parallel to do it.
David Berning’s invention matches the valve amplifier much better to the load with an impedance converter that emulates a near perfect transformer. It gets rid of the problems of the iron cored transformer and its windings. You have noted the audible results. I am struck by how efficient it seems as much of the power put in is converted to sound, and not too much heat.
It is so good that Mark Schneider and the LTA team are bringing this product to us.