Reviewer:
Srajan Ebaen
Financial interests: click here
Sources: 27" iMac with 5K Retina display, 4GHz quad-core engine with 4.4GHz turbo boost, 3TB Fusion Drive, 16GB SDRAM, OSX Yosemite, PureMusic 3.01, Tidal & Qobuz lossless streaming, COS Engineering D1, AURALiC Vega, Aqua Hifi La Scala MkII, Fore Audio DAISy 1, Apple iPod Classic 160GB (AIFF), Astell& Kern AK100 modified by Red Wine Audio, Cambridge Audio iD100, Pro-Ject Dock Box S Digital, Pure i20, Questyle QP1R
Preamplifier: Nagra Jazz, Esoteric C-03, Vinnie Rossi LIO (AVC module), COS Engineering D1
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1, F5, F6, F7; Crayon Audio CFA-1.2; Goldmund Job 225; Aura Note Premier; Wyred4Sound mINT; AURALiC Merak [on loan]; Wyred4Sound SX-1000R [on loan]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; Sounddeco Sigma 2; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Druid V & Submission; German Physiks HRS-120; Eversound Essence; Rethm Bhaava [on loan]
Cables: Complete loom of Zu Event; KingRex uArt, Zu and LightHarmonic LightSpeed double-header USB cables; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Arkana Research XLR/RCA and speaker cables [on loan]; Sablon Audio Petit Corona power cords [on loan], Black Cat Cable redlevel Lupo
Power delivery: Vibex Granada/Alhambra on all components, 5m cords to amp/s + sub
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands [on loan]
Sundry accessories: Acoustic System resonators
Room: Rectangular 5.5 x 15m open floor plan with two-storey gabled ceiling, wood-sleeved steel trusses and stone-over-concrete flooring
Review component retail: $3'549


Fish or fowl? Neither or both?
Pulling a philosophical Hamlet, Wyred4Sound's STP-SE linestage preamp could confuse. Is it active or passive? You see, it doesn't apply any voltage gain until steps 64-80 on its premium resistor ladder volume with relay switching. Yet that doesn't make everything below 64 passive. For fixed i/o Ω and proper output current, the STP runs discrete buffers on either side of its 0.5dB-stepped attenuator matrix. That's different from pure passive preamps. Those combine source switching with nothing but a resistive wiper, ladder or LDR (light-dependent resistor) volume; or magnetic equivalents like tapped transformers or autoformers. A passive's output impedance varies with setting to, generally, prefer short interconnects though magnetic controls like those from Audio Consulting, Bent Audio/Vinnie Rossi and Music First actually increase output current with higher attenuation. The STP-SE is fully balanced from input to output and boasts 164'560+µF of filter capacitance. For this line-level occasion, that could seem massive overkill*. Barely twitching are the noise figures. They're suppressed with a triple ripple-reducing 25A power supply to hit below 6µV in 'passive' mode, below 18µV in active. That's nearly not turned on and state-of-the-art performance! In the fully loaded version—the second stage beyond the basic STP-SE—48 Dale RN55D resistors above the attenuator's 14th step are upgraded to $15/ea. Vishay Z-foil units; the regulators become proprietary discrete jobs "100 times quieter than the stock parts"; four inductors and Schottky diodes go premium; 16 high-freq filter caps are upgraded; the fuse becomes a Rhodium-plated Furutech part, the power IEC a Rhodium-plated bit from the same catalogue; and finally the standard blue VFD display goes green precision OLED. In short, the Stage 2 upgrade throws Wyred's gold-plated parts-filled kitchen sink at the $1'799 circuit. This mimics what they do for their top DAC iterations. Premium parts can double the base price. Giving their customers tiered options supports different budgets and ambitions. Today is about going all out; and in.
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* When most modern amplifiers are driven to full output well below 2V; when most modern sources output at least that if not double or more... it's inelegant and wasteful for a preamp to generate gain only to throw it all away again. Here the Wyred4Sound doesn't bother with gain generation at all. Hence it also avoids its impact on the noise floor. For the rare occasions where gain is required, it's there starting at 64. 63 is unity gain, i.e. equal to the incoming signal voltage. Everything below 63 just attenuates the raw source signal like a passive would but without fluctuating output impedance or limp current drive.

Standard SE without Level 1 or 2 upgrades (also both lower images).


Whilst the IR wand remains generic plastic for all upgrade levels, it controls power, balance, display dim, phase, mute, inputs, HT bypass and volume. All the 3:2 RCA/XLR inputs can be named with up to 16 characters of letters, numbers, spaces or signs. Two each RCA and XLR outputs finish up comprehensive socketry. Finish options are black; or silver with black knob and corners. THD+N/2V is <0.003%, bandwidth linearity ±0.02dB, channel tracking < ±0.05dB, cross talk >106dB. Input impedance is 60.4kΩ, output impedance 50Ω.

With such figures, we just know that the STP-SE's raison d'être isn't as injector of colouration or flavour. We peg it a maximum conveyor of ultra resolution and micro detail; a passive with brass balls that can drive even lengthy interconnects; and with stable output Ω regardless of setting to not modulate a speaker's frequency response. At $3'549 for EJ Sarmento's very best preamp package, its statement ambitions coincide with an attractive price when non-balanced competitors with premium volume controls demand significantly more elsewhere.