: 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 2.04, Tidal & Qobuz lossless streaming, COS Engineering D1, Metrum Hex, AURALiC Vega, Aqua Hifi La Scala MkII, SOtM dX-USB HD w. super-clock upgrade & mBPS-d2s, Apple iPod Classic 160GB (AIFF), Astell& Kern AK100 modified by Red Wine Audio, Cambridge Audio iD100, Pro-Ject Dock Box S Digital, Pure i20
Power & integrated amplifiers: Pass Labs XA30.8, FirstWatt S1, F6; Crayon Audio CFA-1.2; Goldmund Job 225; Gato Audio DIA-250; Aura Note Premier; Wyred4Sound mINT; AURALiC Merak [on loan]
Loudspeakers: EnigmAcoustics M1, Albedo Audio Aptica; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Submission; German Physiks HRS-120, Gallo Strada II w. TR-3D subwoofer
Cables: Complete loom of Zu Event; KingRex uArt double-header USB; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Arkana Research XLR/RCA and speaker cables [on loan]
Power delivery: Vibex Granada/Alhambra on all components
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Rajasthani hardwood rack for amps
Sundry accessories: Acoustic System resonators
Room: Irregularly shaped 9.5 x 10m open floor plan with additional 2nd-floor loft; wood-paneled sloping ceiling; parquet flooring; lots of non-parallel surfaces (pictorial tour here)
Review component retail: $350

With the advent of full-resolution streaming à la Qobuz and WiMP/Tidal subscriptions, the Ethernet link between router and PC has become more critical for SQ. Or so audiophiles who are invested not in WiFi but designer CAT6 cables believe. That incidentally is a subject rife with derision from the IT quarters. Their folks know that the Ethernet protocol is immune to cable quality. Either the connection passes signal. Or it drops out. There's no middle ground. Period. Amen. Those intrepid adventurers who've actually compared generic Ethernet meds to the costlier chems dispute it. This has opened the doors to €4'000+ luxo Ethernet cables. Their buyers are likely hip to this fact. Most ambitious DACs use miniature isolation transformers or opto-couplers on their digital inputs. Here galvanic isolation for USB DACs has become one of them busy buzzy words. Computers are noisy evil doers. Keep their noxious HF chatter away from our pure signal. That's the task at hand. Do you imagine that these same audiophiles have grown restless again worrying whether their music computer's Ethernet port is equally fortified?

South Korea's Soul Of the Music aka SOtM bank on it. Their iSO-CAT6 inline 'black box' inserts a digital isolation transformer plus sundry unreported bits into the Ethernet pipeline. That strips off noise which invades from the routers's ground plane. As Wikipedia reports, "network isolators are installed as part of a copper Ethernet system as galvanic isolators. Network data continues to be transmitted across an electrically non-conducting barrier through the applied principle of electromagnetic induction whereby high-frequency AC voltages conveying data are induced across an isolating gap. The network isolator is therefore a passive device and functions without any requirement of an external power supply."
So routinely the case, industries others than audio are well ahead on this, in this instance for specific safety not sound reasons: "Network isolators are used by the medical industry to protect patients against leakage currents. Network connections between medical devices and Ethernet networks (and other non-medical devices such as personal computers) must be in accordance with IEC standard 60601-1,3rd edition. This specifically deals with medical electronic and electrical equipment and systems. It classifies non-medical devices as potential hazard sources. A specific hazard stems from possible differences in ground potentials between network components, which when not properly isolated can result in a leakage current that can flow through the patient. That is dangerous and potentially lethal. Such voltage differences can also arise through incorrect installation and wiring of network systems, electrical shorting within damaged cables and cabling or shorting between damaged network cables and other voltage sources. Network isolators work to remove this hazard by electrically disconnecting medical devices from a network. Isolators may be used as network accessories, built into medical devices or installed within a medical network system. Networks isolators should be installed as close as possible to the medical device in question."

When SOtM's May Park solicited this review, I volunteered. I had really good experiences with prior SOtM kit. And as WiFi-phobic digs, our household runs a 15m BlueJeans Cable-certified Belden CAT6a link between router and music iMac; and a short 2m strip of the same stuff to my HP workstation where I write to background tunes. Signed up with annual Qobuz and Tidal 16/44.1 streaming services, I'm invested in ultimate sound quality from a hardwired router connection especially for the big rig. Whilst I haven't investigated designer CAT6a to be happy with the cheap current runs, my brain didn't freeze over like hell with SOtM's li'l box. It uses established science. SOtM's upgraded USB card was a proven winner already. And here, the promise of better LAN sound for a relative pittance in hifi coin was too alluring.

It's how they get us time and again, innit? Drat! SOtM's latest remedy would include a short strip of Ethernet wire to complete the connection. Your existing LAN cable leashes router to iSO-CAT6, theirs bridges the short iSO-CAT6 to PC or Mac gap. Nothing could be simpler. Except perhaps for hearing no difference. That happened between our earlier Computer Emporium CAT5 and the current CAT6a with proof-of-compliance print-out. How would today's isolation cookie crumble?