Moving on, the transparency baked into passive preamps was something easily put to the test. Adding it in series with my active preamp was all that took, its own attenuator fully open to act as thru-put buffer. I compared that against without the ARP. Rinse and repeat a half dozen times. Done. My ears didn't register any changes worth holding onto. That too was foretold. The icOn 4PRO I'd used in the exact same way in 2021 was "just an invisible bystander that didn't break, fix or change anything specific that was audible enough to consider its presence meaningful or quite frankly, noticeable. Even if it did something, my ears failed to grasp it. This was telling. A major component's ability to be a part of a system without influencing its sound in any noticeable way is the very definition of transparency. I expected the icOn as buffer to at the very least gently steer my system's voicing into a more illuminated skinnier speedier direction. Nothing like it happened." The ARP proved as invisible as the 4PRO four springs ago. One such elusive design could be lucky coincidence. Two marked a pattern. On transparency, passive AVC are second to none. The ARP also made the point that their kind holds more aces.

My active Trilogy 915R makes my system sound spatially large, quick, impactful, tonally packed and tangibly breathing. As such it nicely complements the two 995R amps and boosts their performance by a significant margin. Without previous exposure to passive AVC, I'd have been certain that the 915R would run circles around the ARP. I'd have expected the passive to sound drier, leaner and inferior. The prohibitively large price gap between them would have factored and me subconsciously biased. Four years later it didn't. Reviewer smarts had nothing to do with it. Experience made the difference. Mine reminded me that the icOn 4PRO had been an absolute monster, a visually inconspicuous financially sane box that one can put safely up against any classic preamp no matter how dear or big and know that it'll firmly hold its ground¹. The ARP was another such nifty little devil with large pointy horns. With its attenuator at 30/61, my system's gain netted stout SPL. While it was spatially more specific, sunnier, somewhat leaner and tonally a touch cooler than the 915R, it staged like mad, was as smooth as it gets yet still generous of colour. It nailed all the fundamentals. Grain, fragility, nervousness and paleness were MIA. I didn't have an icOn 4PRO to compare. If I did, I most likely would have had a really hard time telling them apart. About the former I wrote that "in my system, it quickly revealed itself as being gearing for top-shelf image specificity, complex layering, lucidity, articulation, immediacy, quickness and freshness. These traits translated into copious amounts of air, precisely sketched outlines and overall directness. As naturally centred around quick reflexes and insight, this aroma often comes at a cost to moisture, muscularity, thickness, smoothness and bass reach. The icOn however felt highly coherent, balanced and pleasantly organic. Nothing about it struck me as gritty, sharp, itchy or abnormally zealous. With it my system neither sounded thin nor lifeless, matte, hollow, dehydrated or crippled in any way. The icOn's skill set and avoidance of downsides typical for its zesty voicing spelled high-tier completeness and admirable seasoning way above its asking price."
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¹ I concur completely. In systems which on all counts except volume control work best source-direct because they want no extra injection of anything, the Pál Nagy Lifesaver Audio AVC are the cat's meow and dog's bollocks. They bolt on the missing attenuation but otherwise do nothing. Well, that's not entirely true. Because autoformers convert voltage to current, the more attenuation we invoke (cut voltage), the more current we generate. As we throttle back SPL to background then whisper levels, this increase in current drive seems to explain why AVC excel at midnight levels where the competition washes out. Without needing to hear it, I share Dawid's excitement about an alternate full-featured AVC. – Publisher

Simply replace icOn with ARP and that's how the latter went about its business. It was supposed to. Passive AVC are very specific in what they do and how. As amazing as that was, the ARP still grew on me over the next few days. The more it clashed with my 915R, the more obvious it became that my daily driver was destined to at best match the competitor. But forget all about surpassing it. As oppositely tuned as they were, on sheer sonic competence I rated them equals. Most shoppers who fork out nearly €30K on a preamp would find this a sour pill to swallow. I didn't mind that AVC performance transcends money. The ARP merely reiterated that point. The 915R isn't particularly romantic, calm, warm, cuddly or dark but next to the Hattor it was to some extent. My system with the tiny Spaniard scored higher on resolution, openness, directness, agility, radiance, tight bass and low reach. Higher energy, excitement and intensity followed. By contrast the 915R sounded more voluptuous and liberal on outlines, meatier, spatially somewhat diffuse, relaxed and picturesque. Although the ARP was leaner, more meticulous, shinier, elastic and into spring not autumn hues, it didn't skip a wide colour gamut or textures that make music vivid and joyful. Despite its predominantly quicksilvery and sporty core, it didn't feel artificed nor short on tone or substance. If it were an amp, it'd be a Firstwatt SIT5 or Enleum AMP-23R. I can't say that I disliked the 915R after its skirmish with the ARP. The Brit was more gifted at portraying vocal and instrumental shapes as seductive lifelike beings. Here the newcomer was solid but not quite as good. It's why I think that most listeners would consider the 915R/995R combo as sprinkled by extra elegance so more inviting. Yet each time the ARP was on, the impression was of some veil, residual drag and spatial blur having lifted completely whilst dynamic contrasts widened. That change I only mapped by subtraction.

This difference marked why I thought the ARP quite unputdownable. The sensation was comparable to a filterless widebander in a voluminous enclosure after spending time with nice if regularly ported speakers. On immediacy, insight, control, quickness, clarity and muscle-to-fat ratio, they're not the same. To be clear, the ARP followed the widebander profile. After reviewing the icOn in the past and the ARP just now, it's fitting to call the AVC breed potent accelerators and blur banishers among many other things. All considered, it's quite spectacular what some multi-tapped coils of wire for volume control can do. The question remains whether a system can get by without the extra heft and tonal mass it apparently draws from active preamps. Mine taps into these traits. However, I can't vouch for systems already tuned like the ARP. Perhaps now the combo is too much of the same thing? Odds are that such systems will benefit from more conventional preamps as a means to stay balanced. Or perhaps the ARP has no sound of its own? Perhaps letting us know the true sound of our system without extra resistance and active circuity is all this compact AVC does? In which case, the noticeable performance hike that in many scenarios will follow is a by-product of less is more? Either way, the ARP is a spectacular device. And to be sure, my clear fondness for passive AVC didn't arise from nowhere. The petite cost-effective icOn 4PRO I reviewed in the past not only turned out wickedly good but very dangerous to conventional preamps. As such this British wonder stuck in my craw for years to come. Now that itch is gone courtesy of Hattor's ARP which fits the same profile on all fronts. While it feels and behaves like a regular preamp, it is quieter than most and truly brilliant at lower SPL. It is priced more than fairly considering how sonically accomplished and refined it is. On assembly and aesthetics it scores significantly higher than its tariff promises even justifies. It may be the most affordable commercial AVC to market. Asking for more would be criminal.  Auditioning this impressive stunner prior to anything no matter how fancy is my sincere advice. Lastly, kudos to Arek Kallas for landing this beauty and pursuing rare passive AVC in the first place. It was well worth the effort!