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; S.A.Lab Blackbird SE; Crayon Audio CFA-1.2; Goldmund Job 225; Gato Audio DIA-250; Aura Note Premier; Wyred4Sound mINT; AURALiC Merak [on loan]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; Sounddeco Sigma 2; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Submission; German Physiks HRS-120; Eversound Essence
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 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: $1'799/ea.

Power. Hifi has endless pow-wows about the need and desire for power. My own view is pragmatic: know what you need, then buy that. If your speakers are 97dB early risers and you never listen above 90dB, a 5wpc amp might be that. If your emo boxes run an 18-inch open-baffle woofer and hover around 3Ω, you might need ten times that even at 97dB efficiency. If your box of choice is a compact ported monitor with wicked impedance swings and very ambitious bass alignment to be inefficient plus badly reactive... then 200 watts could suddenly seem bare necessity. That's particularly apt if your room size and SPL appetites are large. If you don't know what you need; what you might own in the future; or in what swanky mansion you might hole up - erring on the side of excess and caution could be just the thing. Lovers of electro/magnetostatic panel speakers like big Magnepans often do that. Their speakers might hit sub 2Ω pot holes not in the negligible treble but at some power-demanding lower freqs. If you do need loads of power; don't want to overspend; and definitely don't want transformer hum from outsized iron, then switch-mode power supplies and so-called class D output stages (where D isn't for digital but simply the next letter after ABC) become very attractive.


Non-fatal attraction. Even though Wyred4Sound's EJ Sarmento already had proprietary statement class D on their 2016 books (here proprietary means in-house solutions, not commercial power modules from the likes of Anaview, B&O/ICEpower, Hypex/nCore, Pascal, PowerSoft, Texas Instruments & Bros.), he still saw fit to overhaul their earlier ICEpower-based top SX-1000 monos. This pair attracts less loaded wallets when the Statement is set at $6'000 or more. Half that buys you today's 'R' suffix SX-1000 twins. 'R' designates a new input board, nextgen WBT binding posts, Kimber TCX wiring, a new anthracite case finish and input impedance up from the earlier 60.4kΩ to now 91kΩ on RCA/XLR alike. That shines a remodeled very toothy grin at valve preamps of higher output impedance.


To rattle not the ESS sabre but specs, we look at 570/1'140-watt 8/4Ω power with an idle noise of <80µV. Dynamic range is 118dB and THD+N 0.2% at full power. Input sensitivity is an unusually low 2.95V. This welcomes active preamps without oversalting this circuit's 27dB of gain. Output impedance is a very low 0.005Ω to promise high damping factor over high-excursion woofers. For all those brawny he-man antics, idle power draw is a mere 15 watts. This stays perfectly chill (ICEpower, remember!) unlike class A behemoths which always dissipate at full power. Due to its notorious inefficiency, the A class usually radiates at ten times the power figure which arrives at the speakers. Could you imagine 5KW of constant draw to match the Wyred's speaker power? Neither could your circuit breaker, utility bill or body temperature.


What despite its first two letters the SX-1000R won't do is oversex your hifi with bling cosmetics. As a people's brand, Wyred4Sound are about value, not prestige. And if you misread yawn fertilizer at the mentions of ICEpower and a revised input/driver stage, the latter has greased bearings on the final sound of otherwise stock class D modules. Just because two amps run the same power modules does not mean they'll sound alike. Just think of the importance a driver tube has on a single-ended triode amp. Because that driver can be changed by an end user to observe the effects, it's an easy example which brings it home. Here EJ has developed quite the rep as a seriously gifted figure skater on B&O's popular ICE rink. That even includes design stints for OEM clients like Peachtree.

To wrap our intro with a proviso, testing the mettle of any muscle amp should mean a show down against a beastly load. That's where I usually fail. I consider dastardly loads an inherent design flaw. I don't want to pay to own 'em. My leanings are toward easy loads which reduce amp requirements. Now I can pursue more exotic amps; and/or save coin on a circuit's smaller simpler version. For how the stork wired my brain in the cradle, that makes more sense. As such, beast mode would normally not be on my menu; unless such a speaker just happened to come through at just the right time. Synchronicity for some R-rated sinchronicity? For once, yes. Think 85dB, 32Hz, one studly 6.5" mid/woofer with ±12mm Xmax, tight dimensions enhanced by synthetic stone, two rear ports: the Mark & Daniel Maximus Monitor MkII. Inbound simultaneously for review, it promised to be most appreciative of SX-type muscle, hence control.


If your gut reaction was a big question mark because stiff load and small speaker didn't compute—you equated big with difficult and small with cute and easy—remember the old 3:2 rule. You can get bandwidth, efficiency and compact size but never all three together. In this case, we have 14.8" x W8.5" x D11.6" dimensions and a smallish mid/woofer claiming near grotesque extension. That relies on a long stroke which escalates pressurization inside a small trapped air volume. It's a brute force approach of overbuilt driver and enclosure; a real tempest in a teapot.

Now add the typical saddle response of ported alignments with their twin peaks in the low end. An 8Ω nominal speaker might hit 60Ω at those peaks. A typical transistor amp will attempt to double its output into 4Ω and perhaps do it once more into 2Ω. In the other direction, it'll halve and halve again and again if not more. It's easy to appreciate how massive bass transients on such a speaker can take a real chunk out of an amp's 8Ω figure. You could be down to 1/10th where impedance spikes. Now add lower speaker sensitivity in general. Suddenly 100w/8Ω could seem skinny whenever music hits a pot hole in the bass. To avoid dynamic compression—going soft and woolly like a soggy car suspension—might mean stacking your power deck with a view at the most demanding band. So napoleonic speakers with forced bass alignments may really do best with oodles of power. At 1'000 watts or more than one horse power into 4Ω, today's $3'600/pr hit the power vs. price index big. And this pair stacks the power deck for even gnarly speakers. SX as in super large perhaps?