July
2021

Country of Origin

UK

icOn 4Pro

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Audirvana 3, Qobuz, Tidal, Denafrips Terminator+ clock-synced to Gaia reclocker, Avatar CD transport, Soundaware D100Pro SD card transport; Preamp: Vinnie Rossi L2 Signature with Elrog ER50; Power amplifiers: LinnenberG Liszt monos; Kinki Studio EX-B7 monos; Headamp: Kinki Studio; Phones: HifiMan Susvara; Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Aurai Audio M1 [on loan]; Cables: Complete loom of Allnic Audio ZL; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 4 x 6m with high gabled beam ceiling opening into 4 x 8m kitchen and 5 x 8m living room so no wall behind the listening chairs
2nd system: Source: Soundaware D300Ref SD transport; DAC: Denafrips Terminator; Preamp/filter: Passive Preamplifier icOn 4Pro SE w. custom 4th-order/40Hz hi-low pass;
Amplifier: Crayon CFA-1.2; Loudspeakers: sound|kaos Vox 3awf, Zu Submission; Power delivery: Furutech GTO 2D NCF; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan];  Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~4x6m
Desktop system: Source: HP Z230 work station Win7/64; USB bridge: Audiobyte Hydra X+; Headamp: COS Engineering H1; Headphones: Final D-8000; Powered speakers: Fram Audio Midi 150
Upstairs headfi/speaker system: Source: Soundaware A280 SD transport; Integrated amplifiers: Schiit Jotunheim R, Bakoon AMP-13R; Phones: Raal-Requisite SR1a; Loudspeakers: Acelec Model 1, Power delivery: Furutech GTO 2D NCF
2-channel video system: Source: Oppo BDP-105; DAC: Kinki Studio; Preamp: Wyred4S16800ound STP-SE II; Power amp: Pass Labs XA-30.8; Loudspeakers: German Physiks HRS-120; Power delivery: Furutech eTP-8, Room: ~6x4m

Review component retail: €1'599 as reviewed

Our sitting ambassador in the Warsaw audio embassy already reported on the fully balanced icOn 4Pro here. Dawid's conclusion? "Just as the Bakoon [AMP-13R – Ed.] before it, the icOn 4Pro is the kind of monster I'd gladly throw against any functionally similar hardware with a mischievous grin on my face in the certainty that it'd win most such fights. I'm clueless what sort of means it'd take to clearly outshine this inconspicuously dressed aggressively priced package. As far as sheer sonic excellence, maturity and completeness go, it sits as high as my reference linestage [active Trilogy 915R – Ed.]. That now sells for roughly £17'000 before VAT and is the best one I know. Okay? If you're in the market for a preamp and don't intend to purposely inject chunky syrupy flavor into your system, auditioning the icOn 4Pro prior to anything else is my best advice."

Aye, Cap'n. "Make it so!"

Being a brainless follower who does as he's told, I did. The end.

Being hopelessly loquacious too, not quite the end. I already own an icOn 4Pro SE with expanded socketry and custom filter to integrate mains and subwoofer in my upstairs system. Curiosity compelled me to also try it downstairs in lieu of a Vinnie Rossi L2. Surprising myself, I preferred it to the direct-heated triodes for still greater lucidness and speed. After brainless and talkative, being lazy is a third personal flaw. So I began to duly resent moving the big icOn up and down the stairs. Why not get a second one but trimmed back to the bare bones of one RCA/XLR i/o each? Wouldn't that make for properly inconspicuous but elite consumption?

It would. So I just did. That's how good this remote-controlled passive from Manchester's Pál Nagy is. If nothing in your overall system tuning wants a course correction and the only thing of remaining interest is to escalate resolution whenever possible—less noise and harmonic distortion, more bandwidth and speed—this small box acts big. And there's something you may not have considered. Like transformers, autoformers transform voltages, currents and Ω between their i/o taps. In today's multi-tapped case, a 15dB cut of the input signal already creates a 5.62 x increase in output current. 30dB attenuation generates 31.25 times more current, 45dB equals a whopping 178.57 x more.

I hear your brain turn over. Did you see the connection?

It's the most likely explanation for an observation often shared by fanciers of passive-magnetic preamps. They excel at staying dynamic and lively at low levels. That's a bit like a high-efficiency speaker. It 'comes on song' a few clicks above mute rather than delays the hear-everything threshold to quite loud.  As one attenuates a magnetic passive to more and more below the incoming source voltage, one simultaneously boosts the current transferred to the amp at an inverse ratio. If source voltage, amplifier gain, speaker sensitivity, room size and desired SPL are in happy balance, listening to significant signal cut improves the sound. It's strange but wonderfully true so an extra bonus for listeners like us who favor lower SPL but insist that those must remain compelling and involving. It makes the icOn 4Pro in any of its guises a perfect hifi whisperer. Henceforth you'll see another one in my ongoing reviews. By now I've been fully cOnned to enter a pleasant state of brainlessness. Even laziness has gotten its due. No more icOn moving about. One per system means that each can stay put or at worst, swap out occasionally when socketry or filter needs require.

My unit on Pál's bench. A sticker on his table lamp says "Engineering: If you're not tired, you're doing it wrong."

Now only my flaw of verbosity needs fixing. Fat chance you say? You could be right. Next life perhaps?