Equipment Report: Linear Tube Audio's New Ultralinear PLUS

When Mark Schneider of LTA reached out to ask if I would be willing to serve as a “Beta Tester” for the new Ultralinear Plus amplifier (UL+) I happily agreed. I’d been following LTA since 2016 when I met Mark at his retail and production facility in Takoma Park, Maryland while attending a conference in DC. Back then Mark was busy launching LTA/Urban HiFi and I was one of the first to hear iterations of David Berning’s ZOTL amplification technology. Shortly thereafter, Mark sent me a UL to try with my Daedalus DA-1.1s and I immediately fell in love. The UL was so good that it made my prior $9k amp sound broken by comparison. When LTA teamed up with Fern & Roby to improve the casework on the entire product line, I upgraded my UL and Mark added a set of Amperex “Bugle Boy” input tubes which elevated the performance further, adding a touch of warmth to the already vivid and tonally pure midrange. Somewhere along the way I put pen to paper to capture my experience with the UL which I posted as a REVIEW here on the Audiogon. I’ve been a happy camper ever since.

But soon after typing “Yes!” and hitting “Send” a tiny wave of dread fell over me. The UL was the best amp I’ve ever used with my DA-1.1s and its virtues became even more apparent after I upgraded to the Daedalus Apollo’s in 2019. I desperately hoped that the upgrades “did no harm” to a sound that was simply captivating. I also wondered how the folks at LTA could squeeze more performance out of this 20 watt wunderkind--yes, the “Bugle Boys” were an improvement, but a very slight one and to my ears the resulting amp was simply impossible to fault. Well, after a week with the UL+ I am here to tell you that I worried for naught. The UL+ preserves the many strengths of the prior unit and builds on them in several subtle, but important ways.

Throughout my audio journey I have discovered that genuine performance improvements typically have some common elements. One of these is a lower noise floor which manifests as less distortion and greater detail. In addition, the enhanced detail is generally presented in a less forward manner--somewhat paradoxically, more information emerges further back in the stage with greater differentiation of layers front to back. This proved half true with the UL+. While the noise level of the UL+ remained unchanged--as in total blackness--the revised amp offers much more detail, particularly through the all important midrange.

One of my go to demo tracks is the song “Gentle Rain” off Diana Krall’s “Love Scenes” (SACD). Listening through the UL+ provides considerably more of the kind of information that renders Krall a living, breathing presence in your listening room. On the standard UL, subtle gradations were evident as the singer emphasized certain musical phrases. The UL+ takes this to another level altogether, allowing the listener to also appreciate incredibly low level shifts in the tone and texture of Krall’s voice that enhance the emotional impact of her interpretation. This is what two-channel audio is all about--connecting the listener with the performer as if it were a live event. In this respect the UL was great--the UL+ is off the charts.

The UL+ also provides a bit more body and realism through the lower midrange and upper bass. I listened to a wide variety of chamber music recordings over the past week, along with solo piano. Many of these were familiar recordings that I lean on when evaluating system changes. In every instance there was a subtle but noticeable natural warmth that accompanied well recorded strings and keyboards. While the upper registers appeared unchanged, the overall impression was an ability to hear more of the resonant tone of the soundboard--a more realistic balance between the body of the instrument and the strings. This was delightful and wholly welcome--I never thought the UL was at all lacking in the “meat on the bones” category, but the UL+ helped me to see that the original version gave up a tiny bit of warmth in this critical region, robbing cello, piano, and even violins of some of their natural texture and tone. Voices, on the other hand, were not similarly affected--all my favorites remained spot on tonally without any added coloration or emphasis.

That said, another noticeable improvement brought to the table by the UL+ is the ability to follow instrumental and vocal lines in complex passages. The UL+ is way more “sorted” than the standard unit. For example, listening to Emmylou Harris singing backup on “Sweet Carolina” off Ryan Adam’s “Heartbreaker” MFSL SACD, she is positioned more clearly on the right stage, beyond the speaker, and the listener can hear every note she lays down over Adam’s vocal. Does anyone sing better harmony parts than Emmylou? Similarly, listening to Mozart’s Divertimento K.563 (Cummings String Trio, Meridian), each of the instruments carves out copious space within the soundstage and the ability to discern individual lines within the tapestry of sound is a piece of cake. Related, but certainly worth mentioning, is an improved sense of timing with the UL+, where the space between notes is as distinct as the physical space between performers. While the standard UL was very, very strong in these respects, the UL+ is considerably better--much to my astonishment and delight.

Finally, the UL+ digs deeper and throws more weight in the deep bass than the standard version. I played numerous tracks with well recorded percussion, kick drum, and stand up bass and in every instance the UL+ extended deeper and with greater precision and musical insight. Plucked acoustic bass on “All or Nothing at All” from “Love Scenes” knocked me back in my chair. Same with “One More for My Baby” from the soundtrack of “Good Night and Good Luck”, which puts Robert Hurst’s bass in the room in a way the standard version could not quite achieve.

I’m not entirely sure what black magic went into the + upgrades. According to the LTA website, some premium parts swapping took place and more capacitance was added but there may be more to it than that--the UL+ felt heavier coming out of the box and runs a bit warmer to the touch than the standard unit. Happily, LTA is offering owners of the standard UL an opportunity to upgrade. From my perspective, the cost is entirely reasonable given the performance enhancements. As I said at the outset, the standard UL was the best amp I’ve ever heard in my system. Unbelievably, the UL+ makes an even more compelling presentation with better timing, spatial cues, separation of musical lines, bass weight, and tonal realism through the lower midrange. If you have somewhat high efficiency speakers like mine the UL+ is probably as good as it gets for amplification--regardless of price.

Thanks for the review. Glad to hear that the enhancement puts "a little more meat on the bones". That was my only criticism of the LTA amps.


I really enjoy your in depth reviews. I’m not the writer you are but your conclusions are the same as mine. As a Beta Tester for the new ZOTL40+. I’ve found similar refinements and couldn’t be any happier with what I’m hearing.  What an incredible value.

@dodgealum, remind us which preamp you are using? I love the UL which I have in the older enclosure with vol control, driven by an eastern electric minimax which adds nice body and drive without reducing clarity, at least to my ears (when compared to using the amp’s built in control). I’m going to email LTA regarding upgrade cost and availability in my version, in the meantime were you given any of those details? Thanks, Ron.
Hey Ron—using a Herron Reference line stage with the LTA. I’ve been a big fan of Keith’s for years having previously owned the prior VTSP 3A (R03). I have heard many great things about the LTA line stages paired with their amps but have yet to try one in my system. 

The new LTA MicroZOTL Preamp is worth a try and with a free trial easy to audition. I will be selling my Vinnie Rossi LIO DHT because it was bested by the MZ Pre.