Linear Tube Audio MicroZOTL MZ3 Headphone Amplifier Review Page 2

MZ3 with Audeze LCD-4z.

The setup

For this review I used the MZ3 as headphone amplifier only, since the speakers I had on hand were the 85dB/W/m Harbeth M40.1 monitors, which are not a suitable pairing for the MZ3’s one-watt output as an integrated and I only had balanced cables in-house for my McIntosh MC611 monoblocs. I used my reference totaldac d1-direct DAC (review HERE) single-ended outputs (being fed by a Roon Nucleus+) into the MZ3 and a number of different headphones from the Sennheiser HD800 to the HIFIMAN HE1000se, but settled on a pair of Audeze LCD-4z planar-magnetic headphones (review HERE) for critical listening. Some will complain about such an expensive DAC being used, but it’s what I have, what I’m used to, and that’s why it gets used.

I started my MZ3 listening sessions with a lot of acoustic albums as I wanted to see how accurately it could translate everyday instruments like six-string guitars, saxophones, kick drums, cymbals, pianos and of most interest to me: the human voice. Simple analog, singer/songwriter albums that are plainly mic’d and lack electronic retouching are a Grail of sorts for me because there is nowhere for crappy recording, production or mastering to hide. The whole process is laid bare in stark relief – what you see is what you get.

Aerial Boundaries (TIDAL, 16-bit/44.1kHz), released in 1984 by Michael Hedges, is a great place to start ascertaining an amp’s timbral/tonal/textural abilities in sound reproduction because not only is it one of the most spacious acoustic-guitar recordings I’ve ever heard, it was also nominated for a Grammy as Best Engineered Recording… you see what I’m getting at. The first time I heard it at a friend’s place I was disconcerted. You see, after listening for a couple minutes I asked to see the album cover and find out who was accompanying Hedges, only to realize that all the music I was hearing was coming from one man and one guitar. I’ve heard it many times on numerous system iterations over the years (both analog and digital) so when I heard the familiar tonal/pitch inflections of Hedge’s plucking, finger picking, slapping, clawing, hammering – breaking strings like twigs underfoot on a forest floor – through the MZ3/LCD-4z combo, I knew LTA had gotten one of the most critical (to me, anyway) parts of the amp’s voicing locked own; the strings and wooden body of a guitar. And in my experience, if you fool me into thinking I’m hearing a real guitar floating in the space between my ears through a set of cans, then just about everything else falls perfectly into place timbrally; brass, ivory, drum skins, catgut or vocals.

That said, regardless if it was acoustic, jazz, pop, rock or EDM, there is no mistaking a noticeable linearity to the perceived frequency response from the MZ3 – setting it apart from what I would consider a traditional tubed-output sound. There was a speed/tightness/grip and lack of tubbiness to the lower Hz that put me in mind more of solid-state amplification, so in use, it seems that the claims of ZOTL’s improved bass control over traditional output transformers has real-world merit. As with all things in hi-fi, YMMV.

Cat Stevens 1971 LP Teaser and the Firecat (TIDAL, 16-bit/44.1kHz), introduces itself with one of my favorite guitar openings at the start of “The Wind,” which sees him weave an acoustic interplay with Alun Davies – long time friend and mentor/cohort – also on six-string. The closeness in the mix of the two guitar bodies resonance can make them difficult to pick out separately in a spatial sense, but here the MZ3’s timbral clarity and transient detail allows one to more easily pick out the differing tuning between the two player’s guitars. Instrument body weight of the two is also slightly changed-up, further delineating the ‘woody’ character between the two guitars and the way they are being held against each artist’s body in the 3D-axis of the recording. Once again, there was no one part of the frequency range that particuarly leapt out in playback, while a reasonably spacious recording, Teaser never felt artificially goosed with dimension in the upper registers – if anything, tracks like “Moonshadow” sounded more realistic in its presentation thanks to the lack of exaggerated air to higher notes.

Kanye West is polarizing at the best of times. Between personal demons, self doubt and an ego like a Volswagen Beetle trying to fit through a cat door, he is, in turn, superstar pop icon and all-too fragile human being. Following the death of his mother from complications arising from plastic surgery in 2008, West stripped everything down to the rivets from a songwriting perspective and gave emotional, vocal auto-tuned birth to 808 and Heartbreaks. This album has all the unique aural fingerprints (read; plastic sounding and boomy) that only a Roland TR-808 drum machine can leave behind for investigation. This whole album features such a mish-mash of gospel backup singers, West’s altered multi-tracked vocals, blips, bleeps, electronic fractal noise and ridiculous, distorted bubble-gum bass that lesser amp designs can struggle.

Things were reasonably tight on tracks where I expected them to be rattled (“Heartless” for example). Having listened to this album in heavy rotation off-and-on since it came out, it’s one of those LPs that I need to crank the whole way through at least once or twice a year. My current two-channel set-up consists of 600-watt monoblocs with massive output transformers, so I’ve got a solid reference for what 808 can sound like through loudspeakers. I’ve also got an dCS Bartók DAC/Headamp in-house which has an solid-state grip on the bottom end, so headphones are covered. While full of high-tonal contrast, the songs tend to a dense, layered payout that can be mishandled, jumbled or just plain trampled on (“Paranoid”). If you crank this on a great system, the rewards are tangible and cathartic; On a lesser system, you just become frustrated at pitch/tonal gaffes, blown bottom end, lacklustre transient speed or blurring. Despite West’s best efforts to confound playback, it was thwarted by the LTA amp which kept instruments siloed, bass tuneful and allowed a window of true musical resolution through electronic hash, all while maintaining a musical lock on melodies and the overarching emotional tenor of each cut.


The LTA MZ3 – highly recommended for an end-game solution.

As I wrote in my review of the Audeze LCD-4z; “They pretty much give you exactly what you’re feeding them without flourish, attenuation or goosing.” Translation: they’re not going to make a shit recording sound sublime. They will ruthlessly reveal shortcomings in recording/mastering and poor amplification, but they do it in a sophisticated and classy way, without ever making you wince. They’re at the current pinnacle of audio engineering excellence and a pair of headphones which I consider to be among the best I’ve ever had the opportunity to hear. Pairing them with the Linear Tube Audio MZ3 wasn’t merely because they cost roughly the same price, or shared the letter ‘z’ in thier name. it was because they were a holostic, sonic ecosystem. One complimented the other perfectly in my estimation. Does that mean the MZ3 didn’t play as nicely with other headphones that were current hungry or more difficult to drive? No. It came down to the 4z allowing every facet of what the MZ3 had on tap to be revealed without adding anything to its flavor. I can say without hyperbole that in my experience this is a headphone amplifier with few peers at this price point: it is an honest and forthright amp that does that unique job of bringing warmth to music without sacrificing resolution. It excels at balance in its frequency response, does clean, tight bass without exaggerated tube bloom and has flesh-and-blood treble and midrange reproduction capabilities that should leave both solid-state and tube-amp fans feeling satisfied that they’ve dropped their hard-earned coin on a piece of gear that has the flexibility to drive pretty much any headphone you can throw at it, thanks to its ZOTL circuit design. The fact that it can run as a preamp or even an integrated amp with proper speaker-matching only adds more to its value. Highly recommended.


  • Inputs: Three Stereo single ended RCA high quality connectors using sealed, silver contact relay control for a short signal path
  • Outputs: Headphone 1/4-inch, Dual preamp RCA outputs single ended, Stereo speaker binding posts
  • Amplifier class: Push-pull Class A, no feedback
  • Sensitivity: 0.6V RMS [full output]
  • Output impedance: (measured @ 0.5A, 60 Hz) 2 ohms for headphone and speaker outputs, 50 ohms for preamplifier outputs
  • Input impedance: 50k
  • Volume Control: Stepped attenuator constructed of 1025 steps of 50 ohms, with 100 positions selected to provide very fine resolution at the lowest volumes and a logarithmic control for higher volumes.
  • Balance Control: 100 per cent channel isolation using stored differences of volume values. Maximum balance differential is 16 steps
  • Power Supply: Linear supply user-switchable between 110/120 and 220/240 (100V linear supply available for Japan).
  • Power Supply Output:  12VDC 3 amp
  • Hum and noise: minimum 60mV RMS or 90dB below full output (20Hz-20kHz)
  • Power consumption from AC power source: approx. 50W
  • Power output: with 4-ohm load: 1W, 1 per cent THD, with 14-ohm load: 0.5W, 1 per cent THD
  • Frequency response full power: (4-ohm load) +0, -1dB 10Hz-20kHz, (14-ohm load): +0, -1dB 5Hz-50kHz
  • Voltage gain:  (4-ohm load): 10.3dB, (14-ohm load): 12.4dB
  • Price: $3,700 USD

Linear Tube Audio
7316 Carroll Ave. Takoma Park, MD, 20912

Simply Nobody's picture

Stereophile has reviewed another model LTA microZOTL with measurements :-) ........

Simply Nobody's picture

It would be interesting see a comparison review with the Manley Absolute tube headphone amp, $4,500 :-) .........