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Truth serum: For linestage assignments and a firm reality check, any serious reviewer really ought to keep a superior passive on hand. Mine is John Chapman's brilliant but now discontinued Tap-X autoformer control with 61 x 1dB steps and comprehensive remote control including balance. John's very classy all-metal wand happens to run the same IR codes for ± volume and mute as Dan's plastic version. This graced me with a free luxury upgrade for the LS100. Sweet. Signal paths for this comparison were iMac with PureMusic 1.74a in hybrid memory play and pre-allocated RAM; Burson Audio HA160D with volume control bypassed; LS100/Tap-X; KWA100SE; Tango R speaker. All low-level devices except for the computer plugged into the Polish GigaWatt PF-2 power bar, the amp into an equivalent Furutech RTP6.

Instead of pretending at subtractive/additive comments, I'll only describe how the tubes distinguished themselves from a proven autoformer volume control for which at least theory would predict the least amount of signal loss/manipulation. Going in one expects differences. Why otherwise bother with tubes? It's not as though most modern source/amp combos require any added gain. If you figured on big enhancements here you'd be surprised. In the LS100 the 6SN7's fatty big-tone rep at least with my Create/Synergy glass—Shuguang's Black Treasures ought to be quite comparable—was played down. Against the Bent the ModWright was less sculpted on dimensional relief. Its noise floor with ear on drivers was a bit higher than the passive which for all intents and purposes wasn't on. The LS100 would cloud over sooner at ultra-low midnight whisper levels. Conversely the LS100 had the slightly weightier bass and the overall meatier balance. It also traded the Tap-X's drier starker but more holographic take for more liquid textures plus some connective tissue (harmonic distortion).


The passive was airier and more lit up on top. Instead of fluffier textures however as those qualities often create, the autoformers were clearly less moist than the tubes. The 6SN7s were darker and warmer but far less guilty of the opacity filter which my best 300Bs had inserted in a comparison between PX4 and 300B in an earlier review of the Eddie Current Balancing Act preamp. On dynamic scaling if not speed the LS100 seemed to lead the Tap-X but it was impossible to determine whether that was actually amplitude swing or simply greater perceived mass. Importantly the magnitude of these differences was less than expected.

If the Tap-X was my shot at max resolution, the LS100 took away and added. Naturally I couldn't measure percentages. I can reflect only on what seemed subjectively more important. With the KWA 100SE, the less stark (softer?) textures, the slightly heavier bass, the more forceful apparent dynamics and the more fluid rather than charged progression better supported the believability of the hifi illusion. The more expansive treble and the dimensionally more crystallized depth perspective of the passive were more spectacular but also more aloof and cool. Incidentally I'd feel quite the opposite with my 300B, EL84 and 6550 valve amps. There the passive qualities are the better match. When applying these particular descriptions the operative term is quite gently. The LS100's harnessing of tube-based tone is more of a distillation than wholesale exploitation. The softening and thickening action so typical for valves is quite mild. Here it builds out a bit of body and coats the sounds in mild sheen like morning dew but does both without dragging down perceived timing.

Sibling rivalry: What the LS100 ceded to the Tap-X on audible space, sharpened articulation, top-end openness and raw resolution the DM36.5 made up for. While I hoped to crown the half-priced stable mate victorious, I objectively couldn't. Heck the physically smaller 36.5 power supply alone outweighed the taller deeper LS100 which arguably does update/upgrade the elder brother on features and aesthetics.


That said, the twin boxer did sound more solid-statish particularly in its handling of the upper ranges. While informativeness increased so did the potential for occasional album-enforced glassiness. The 6H30-fitted machine with its far smaller potential for valve rolling was the more articulate and crisp but texturally also drier. It wasn't really leaner on tonal balance—its bass exceeded the LS100 on mass and reach—but expressed differently weighted aspects on the transient/sustain/decay axis.


There was more emphasis on attacks, less envelope on bloom, more visibility on decays. The 'reduction in the middle' sounded leaner, the more sharply drawn attacks more transistory and the more illuminated and aerated presentation was dimensionally more resolved. Cooler and more defined but texturally less elegant and suave, in the end I favored the LS100 with its matching amp.


Audiophile check list in hand there was no question that the DM36.5 is more resolved and dynamically superior. Even so certain applications—the KWA100SE being one of them for me—could prefer the LS100. Switching DACs from Burson to Weiss diminished the inherent mild warmth and upshifted the presentation towards just a tad more DM36.5-type light whilst giving up midband density. Bottom line, against the Swiss neutrality of the AVC the DM36.5 was more honest but the LS100 more beautiful.

In these comparisons centered on ModWright's Mosfet amp the LS100 struck me as perfectly matched. Obviously that's no coincidence. I was simply happy that my ears and those of the designer agreed once more. With a respectful nod at the LS/DM36.5 for its higher fidelity, it does seem due for a cosmetic makeover to match the growing lineup on the backlit logo, the new bigger rotary controls, the recessed push buttons and the revised footprint. In my stable the Tap-X already—and still—occupies the top spot on lucidness, speed and magnification power. On that flavor I'm all set. The LS100's more audible 6SN7s and tube personality thus serve me better than the more neutral 6H30s in the dearer two-chassis model. For me the LS100 is subjectively better then. Time to retire the DM36.5 and clear some shelf space. This hasn't yet touched on headphone drive nor the forthcoming $1.000 DAC module whose 24/192 asynchronous USB input run through the preamp's tube output stage should have the PC audio crowd's (and my) attention. The design will also include proprietary data input clocking and buffering to maintain jitter levels below 20ps. An external DAC design also tube-based will be offered after that and is projected to come in below $3.000.
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