Review: A ModWright Stack—LS 99 Balanced Tube Preamp | KWA 99 Monoblocks

Purity and power.

There’s a directness to the sound of the ModWright stack that traveled with it through every pair of speakers I paired it with. Purity and power.

The ModWright stack is a hybrid affair, marrying the LS 99 Balanced Tube Preamplifier that combines a pair of JJ E88CC/6DJ8 miniature nine-pin medium-gain dual-triodes and a single Sovtek 5AR4 for the tube rectified solid state outboard power supply with the KWA 99 Monoblocks that offer 100 Watts of MOSFET-based power into 8 Ohms, doubling down into 4, and run in Class A/B but “biased as much into Class A as possible for best sound”.

It’s fair to say that a sizeable portion of the space inside the KWA 99 Monoblocks is taken up by the power transformers that also account for the better part of their 35 pounds a piece.

A total of 4 inputs (2x XLR, 2x RCA) and 4 outputs (2x XLR, 2x RCA) fill the LS 99’s backside along with a Home Theater Bypass input for movie buffs, 12V trigger outputs for leashing additional ModWrights together, and an 8-pin inlet for the outboard power supply (a 4′ umbilical cable is included).

Each KWA 99 offer a single balanced XLR and single-ended RCA input, a pair of 5-way speaker binding posts, and a 12V trigger input to control on/off status along with other functions for other ModWright products, like the LS 99, with a single remote. A dial allows you to dim those VU meters and a toggle switch turns the internal blue LEDs on or off. I chose to let everything glow.

I also dig the blue heat sinks that run down the KWA 99’s outside sides.

The stack got to play with a bunch of speakers including the review Audiovector QR 7 SE (more info), Piega Coax Gen2 411 standmounts (more info), as well as the Barn resident DeVore O/96 (review). Front end duties were handled by the Auralic ARIES G1.1 (review) feeding either the review LAIV Harmony DAC (more info) via a length of AudioQuest Carbon USB cable or the Barn resident totaldac d1-unity (review) via a length of AQ Diamond AES cable as well as the Mola Mola Tambaqui (review) acting as streamer and DAC (full system and Barn details).

If I had to pick a favorite speaker partner with the ModWright stack I wouldn’t. Yea, I can be that way especially so when its sonic character remained so consistent even when driving three very different sounding pairs of speakers. But let start with the DeVore O/96 since they are my reference and I’m aware of more than a murmur tickling around the internet about how the O/96 are supposed to be driven by tube amplification. Some even suggesting partnering the DeVores with solid state borders on the sacrilegious! Here’s what I have to say about that—poppycock! Harsh, I know.

The fact of the matter is I’ve paired my O/96 with lots of amps of all kinds over the years and what they like best is good sounding amplifiers. And good sounding amplifiers come in all kinds. All kinds, so if you ever hear or read about how the DeVore’s only work with tube amps you know you’re talking to someone who doesn’t have experience with lots of different amps and the O/96.

Josephine Foster is a lovely, quirky singer/songwriter with more than a hint of nostalgia mixed in but twisted, the kind of sound that would not be out of place in a David Lynch movie (that’s a compliment). Faithful Fairy Harmony from 2018 is an extra special delight with Foster’s lovely, quirky voice accompanied by herself on guitar, piano, organ, harp and autoharp with a number of guest artists adding even more flavors to this rich stew in song.

From the liner notes:

Josephine raises a stained-glass lamp and shepherds us spelunking the depths of spirit in this four-part double album. Following the fame of her voice are choruses of winged entities (and a space shuttle) that ascend and descend a maze of spirituals: ritual prayers, blues laments, vestal hymns and jubilant benedictions. The edges of the natural world are revolving backdrops from which our narrator perches upon symbolic precipice or saunters desolate snow-blanched forest, exploring eternal themes of mortality and morality, beneath the moon and in occasional dialogue with a mysterious lord of love, an ambiguous mystical figure.

Exactly. And with the ModWright stack driving the DeVore O/96 all of this beautiful, subtle, and sublime otherness filled the Barn with lifelike energy, spark, and delight. The ModWright offers up a very finely resolved and nuanced sound image, a very engaging balance that never felt overly detailed or unnaturally hyped. Or to put it in the positive, the ModWright stack sounded nicely natural and rich, especially when paired with the totaldac d1-unity. I’ll talk more about the LAIV Harmony DAC in that review but when compared directly to the 4.6 times more expensive totaldac, unfair I know, you get a very clear picture of the gulf that exists between the way each reproduce music. This system—ModWright stack/DeVore O/96/totaldac d1-unity/Auralic ARIES G1.1 all strung together with AudioQuest cables—presented the complex tapestry of sound that comprises Faithful Fairy Harmony with refined elegant beauty. Nice.

Piega Coax Gen2 411

The Piega Coax Gen2 411 Standmount Speakers are a very different speaker when compared to the O/96, or so says Captain Obvious. While I’ll dig more deeply into their performance in that review, when driven by the ModWright stack, the relatively small Piegas with their 6” woofers and C112+ coaxial ribbon mid/tweeter did a fine job communicating Kim Gordon’s cool slow badassness in Barn.

The Collective, released back in March on Matador, gives me hope for being 70 as Gordon sounds even more energized and wise than in her Sonic Youth days, and that band majored in energy. Super chunky guitars, barely controlled distortion, synths, and even more distortion with Gordon’s spoken-sung vocals coolly layered above the fray, this is dangerous music meant to be played loud. (!) And the ModWright’s own cool control came through loud and clear with the standmount-sized Piegas offering up a nicely physical feeling presentation with lovely liquidity and real bass heft. Compared to the O/96, the Piegas sound more lit up, it is a coax ribbon after all, but not harsh, not sibilant, or overly etched and the overall sound was kinda surprisingly full range, physical, and seamless. And it’s worth noting that this music, even with all that noise and distortion, clearly benefits from quality reproduction as each element exists in space and resounds within that space with clearly defined sonic cues. As Sun Ra said, space is the place.

Audiovector QR 7 SE

Moving to yet another flavor of speaker, the Audiovector floorstanding QR 7 SE are a 3-way, 4-driver bass reflex design that sports an AMT 2 tweeter that “features a rose gold-plated dispersion mesh, which works as an S-Stop filter” that helps control sibilants according to the company, a 6″ Pure Piston midrange driver, and a pair of 8″ Pure Piston bass drivers. Sensitivity is a claimed 90.5dB with a rated frequency response of 23-52 kHz. A tower of power?

Mannequin Pussy’s I Got Heaven, also from March of this year, is another blistering beauty of a record. Guitar, bass, drums, synthesizer, and vocals from Marisa Dabice, Kaleen Reading, Colins “Bear” Regisford, and Maxine Steen with additional vocals and violin courtesy of Macie Stewart (Finom) have more than a touch of Sonic Youth energy and this record is a high point, for me, in their oeuvre. Think major attitude with the chops to back it up. The Audiovector QR 7 SE sounded as if they were made with Mannequin Pussy in mind, as their full-range performance really drove all this noisy (bad) attitude home. There’s no fair comparison to be made between a floorstander packed with drivers compared to a standmount when it comes to moving air with real music power and the ModWright stack drove the crap out of the Audiovector with Mannequin Pussy behind the wheel. We’re talking about real music power, a physical yet nimble presentation that nearly had me jump out of my seat when the title track kicked off. Yeow!

DeVore O/96

Compared to the recently reviewed Naim stack (review), I found the ModWright stack offered more excitement regardless of listening level when paired with the DeVores. This added excitement was the result of more incisive drive, what sounded like a quicker transient step, and a dash more color to timbre. Granted, the Naim gear is a solidity champ with an excellent sense of clarity so we’re talking about sound flavors and not sonic absolutes, but for my tastes and speakers, the ModWright stack drew me deeper into the listening experience where the gear gave way to pure music energy more than the Naim. Interestingly, both offer 100 Watts of output power which clearly tells us absolutely nothing. Since I brought up the more expensive Riviera Labs Levante integrated amplifier (review) in the Naim review, it’s worth noting that no other integrated amp or stack has yet to come close to the Levante’s shocking holographic sound.

Weavings 2 is “A durational improvisation structured in the manner of a long fabric of sound, Weavings is conceived by Nicolás Jaar. The original project was recorded in 2020 during the pandemic, with performers joining remotely from around the world.” This is spider web delicate music from artists Aho Ssan, Angel Bat Dawid, Antonina Nowacka, Khyam Allami, Nicolás Jaar, Oren Ambarchi, Pak Yan Lau, Paweł Szamburski, Raphael Rogiński, Resina, Tomoko Sauvage, and Valentina Magaletti that whispers into the listening room with crackling, ethereal beauty. This is also the kind of music the O/96 eats for lunch as they are supremely adept at revealing the subtlest of sounds and timbral flavors. Micro-events R-Us. And the ModWright stack proved more than up to this gentle, subtle task with a presentation that was at once airy, light as a cloud, yet physically present in a believably tactile manner. Very nice indeed.

As has become a kind of ritual, I closed out my time with the ModWright stack paired with the DeVore O/96 by playing through a bunch of favorite tracks from my ‘test track’ playlist hitting up old favorites from Tom Waits, Einstürzende Neubauten, Shannon Lay, Lana Del Ray, Tomberlin, Lucinda Chua, and so on (wink) and I nearly floated away on wings made of music that transformed the Barn into a resoundingly lovely music box.

Throughout the ModWright stack’s 2-month stay, they filled the Barn’s A-side with the sounds of sweet, pure, powerful music regardless of the speaker in play. If you value control coupled with delicacy and plenty of drive paired with timbral rightness—purity and power—the ModWright LS 99 Balanced Tube Preamp/KWA 99 Monoblock combo has a lot to offer.

ModWright LS 99 Balanced Tube Preamplifier
Price: $6500
ModWright KWA 99 Monoblocks
Price: $9000/pair
Company Website: ModWright

LS 99 Features

(2) XLR Fully Balanced Inputs.
(3) RCA Inputs.
(1) RCA HT/BP (Home Theater Bypass Input).
(2) XLR Fully Balanced Outputs.
(2) RCA Outputs.
Dual Remote 12V Trigger Outputs.
Remote Control: Volume, mute and trigger outputs.
Tube Output: 6922/6DJ8/7308/E88CC
Tube Rectified: 5AR4/GZ34 and Equivalents.
Pure Class A.
External Power Supply.

LS 99 Specifications

Gain: 11dB.
Frequency Response: 20Hz – 150Khz flat.
Input Impedance: 30K.
Output Impedance: 100 ohm.
Noise Floor: -110dB (unweighted).
Dimensions: Preamp = 10.5”W x 4.5”H x 12”D. (Depth includes 1.25” knobs and .75” RCA’s. Height does not include exposed tubes. Overall height varies by tube mfr).
Dimensions: External Supply = 7”W x 9”D x 3”H
Weight: Preamp = 17 lbs. External Supply = 11 lbs.
Combined Shipping Weight: 33 lbs.
Umbilical: (1) 4 ft. umbilical with 8-pin Switchcraft connectors.

KWA 99 Features

(1) RCA input.
(1) XLR input.
RCA and XLR inputs are transformer coupled to input stage with floated ground.
(1) Pair 5-way Binding Posts – Positive (+) Red, and Negative (-) Black. Not bridged.
(1) Internal Led On/Off Switch: Disables internal LED’s.
(1) VU Dimmer Knob: Adjusts brightness of VU meter, to zero brightness.
(1) 12V Trigger: External 12V input power on/off trigger.
Class A/B Operation. High Class A bias, but not pure Class A.
Dimensions: 10.5”W x 6.5”H x 16”D – Height includes footers. Depth includes 1” binding posts.
Product Weight: 30 lbs / Shipped Weight: 35 lbs

KWA 99 Specifications

Gain: 26dB.
Frequency Response: 10Hz – 150Khz (+0, -1dB).
Input Impedance: 47K.
Noise Floor: -90dB (Unweighted).
THD: < .05%