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Passive passion. The concept alone predicted sonics to a 'p'. In no-gain mode Aurix is a passive preamp with properly buffered volume control. It simply happens to drive headphones, not an amplifier. In gain mode it's still a passive preamp but now acts like a transformer-volume control whose 6dB step-up gain got bumped to and fixed at 10dB whilst volume control switched to a conventional pot. But unlike common passive aggravation, Aurix's pre/post buffer relative to the Alps avoids variable impedance. With it related response shifts are history. Call it a constant-Ω volume control with ¼" jack and optional 'turbo' boost. It logically follows that everything about discussions on passive versus active preamps applies. This was brought home almost instantly when I contrasted the Aurix and Wow Audio Lab's active L1 driven from the 2Vrms outputs of my Metrum Hex (the L1's voltage gain is 15dB, i.e. only slightly higher than Cees' transformer step-up ratio).

Specifically Aurix couldn't match the material heaviness of the Asian Jeff Rowland lookalike whose review stated that "...said gravitas—what one might equate with big-woofer'd Harbeths versus a small Raidho 2-way monitor—really is the dominant quality. The associated sense of calm is its surrounding flavor. It's like the unhurried confidence of a slightly fat but firm man completely at ease with himself taking up space. There's nothing hasty, nervous, jittery, jagged or small about him or this." With my headphones this translated most noticeably in the bass, alas not on extension but shove, mass and gravitational pull. Simon Lee of April Music put the effect as follows in my intro for his Aura Note V2 review:
With beyerdynamic T1 and hard-wired ALO Audio leash.
"I want to make people feel the way we felt back in the 70s with vinyl. We've since lost that feeling of being there, the musical ambience even though we now have high resolution and huge power. I have thought about this for more than 30 years. I think the solution ought to be that bass extension must reach lower than it usually does in audio so we may feel the true ambience of being there, the venue of where the music took place. Next the musical nuance of the mid and high frequencies should be added atop this solid bass foundation. Finally we must refrain from detail overload which can make people nervous and fatigued." Walking his talk, Lee added defeatable analog bass boost to the headfi circuits of his DP1 and HP100MkII. This does exactly what my L1 quote described as the gestalt difference between a big-woofer Harbeth maxi monitor and a small-woofer Raidho mini monitor. The Raidho shifts calmer meatier substance into more energetic leaner lucidity. One ride is built for 'analogue' comfort, the other for 'digital' speed.

With Sennheiser HD800 and ALO Audio leash.
It's on the latter count where Aurix scores big. Take Turkey's Bülent Ersoy or Spain's Falete. Both are trans-gender singers with female mannerisms coupled to a male's low-end power that's unusually continuous into the upper registers. Over the L1 Bülent's exceptional tone mass dominated. With Aurix the attack intensity and harmonic fire in the forceful often extended warbling peaks moved to the fore. Falete's Flamenco was more hair-raising and 'on edge' with the Metrum, more grounded and majestic with the WAL.


The latter's greater bass heft anchored the presentation in the recorded venue. I'm there is the catch phrase. The former's nearfield milieu of close-up intimacy and transient suchness created they are here. These aren't word games. They're pointers at a shift in listener perspective. On general flavor Dan Clark's Alpha Dog and my Audeze LCD-2 shared common ground with the L1. Sennheiser's HD800 and HifiMan's HE-500 were kinfolk of the Aurix. Do you favor like+like augmentation? Match them as such. Want opposites to attract? Cross pollinate.

That's the basic setup. To quote once more from my L1 review, "... its circuit is decidedly active. As it should in my book, it does something. Otherwise you might as well go source direct. Its own action meanwhile is the previously described gravitas enveloped in an aura of tangible calm. It's a settled comfortable weighty sound whose focus is on tone mass and natural physicality. It's not centered on hyper vivid, otherworldly ethereal or youthfully charged." By contrast Aurix does go source direct. Coming off the matching Hex DAC, if it were a speaker it'd be a Voxativ or Rethm, i.e. a zero xover 100dB efficient widebander of uncut reflexes and directness. Tapping instead into Burson's beefy Conductor injected a heavier denser flavor. In widebander terms we'd now be on soundkaos or Ocellia turf. Because a hi-Ω headphone like the Sennheiser yells at you at levels well below unity gain (the signal strength of your CD/DAC gets too loud and must be knocked down), this makes it very easy to compare no gain to step-up gain. The insertion of the transformers has a very slight softening/sweetening action. For loads that don't need its added loudness, the 10dB boost can thus become a subtle aroma infuser. For the most direct hit go fully passive. For a click down from max focus and adrenaline go gain.

With Burson Conductor and Audeze LCD-2 again with ALO Audio leash.
That said and similar to how I remember FirstWatt's F4 'transconductance' amplifier—a pure current buffer without any voltage gain—the Aurix type of directness isn't as charged as for example the current-mode Questyle CMA800R. Yes the warmer meatier L1 asserts a clearly greater degree of calm and non-humid warmth which make the Aurix jumpier and quickened by comparison. And, the CMA800R is still more incisive and crystalline to ratchet up rhythmic tension and transient impact. There's thus a progression. Aurix majors on the clarity, directness and a reduction of overall weight particularly so in the bass which are all key attributes of passive preamps. But on PRaT Aurix is still mellower and 'easier' than circuits which were groomed for maximal drive and the type of frontal propulsion which can get a wee bit relentless. Which leaves the questions what loads the Aurix will actually drive; which ones even in 10dB gear don't quite make it up the hill if you're a banger; and how much more specific we can get on its sound.