One question always seems to arise when audio enthusiasts get together: “Do cables matter?” This topic tends to elicit polarized responses; you, too, probably have a strong opinion on the matter. Nearly everyone agrees that for safety reasons, cables must, at a minimum, meet the criteria set by component manufacturers. However, when it comes to the sonic performance of aftermarket cables, the conversation can become heated. From firsthand experience I know that’s what you need—experience—to form an informed opinion. Some aftermarket cables I’ve tried had little impact, while others made a significant difference—often for the better, sometimes for the worse.
The key question is not “Do cables matter?” but rather “How much do cables matter?” Specifically, in what ways and to what extent does a given cable affect sound quality? Aftermarket audio cables are like seasoning—a touch of refinement in the quest for perfection. The proof, of course, is in the pudding—or the playback.
The subject of this review is the Signature Supremus Zr loudspeaker cable from British audio manufacturer QED. In 1976, three years after its founding, QED released its first specialized speaker cable, the QED 79 strand cable. Now, almost 50 years later, QED produces a full range of analog and digital cables for both consumer and professional markets. On its website QED has a page titled “Why Cables Matter” that provides links to white papers on cable design in general as well as on specific products, including a paper on the Supremus Zr.
Introduced in mid-2024, the Supremus Zr is QED’s current flagship loudspeaker cable. For this review QED sent me a 3m pair (US$2700, CA$3499.99, £1799, €1835). The Supremus Zr is also available in lengths of 2m, 2.5m, 4m, and 5m, priced at US$2100, US$2400, US$3300, and US$3900, respectively, for a pair.
QED offers four series of loudspeaker cables: the entry-level Connect Series, the Performance Series, the Reference Series, and the top-tier Signature Series. In addition to the new Supremus Zr, the Signature Series includes the Genesis Silver Spiral loudspeaker cable. A 3m pair (US$599.99) accompanied my Supremus Zr sample pair for comparison.
Key features
The Zr designation of the new Supremus hints at the salient new feature of this flagship speaker cable, zirconium-derived parts; there are several others:
Zirconia Airloc design. Zirconia (zirconium dioxide) is used for the connector barrels and cable boots of the Supremus Zr. It’s also used in luxury products like watches and fountain pens as well as in the automotive and aerospace industries. Zirconia is known for its high mechanical strength, excellent resistance to high-temperature, and durable, scratch-resistant mirror finish. The black zirconia variety used in the Supremus Zr, dubbed “ceramic steel,” offers more than lustrous looks and hardiness. It is electrically inert and therefore not susceptible to distortion-inducing eddy currents.
Cold-weld system. The Supremus Zr cable is offered only in pre-terminated lengths, with either banana plugs or spades. It uses Zirconia Airloc connectors, which are attached to the cable by a chemical cold-welding process that eliminates air from the cable–plug interface. This prevents oxidation of the conductors’ surface, 99.999% oxygen-free silver-plated copper, ensuring optimal connection and performance. Using a high-pressure compression termination tool, the Airloc process creates a chemical bond between the conductors and the plug, without exposure to oxidizing air. The QED Zirconia Airloc banana plug features a new zero-insertion-force twist-to-lock design that securely clamps the rhodium-plated beryllium copper pins into the speaker binding post, providing ample contact area.
Rhodium-plated locking design. Rhodium (Rh), a naturally occurring rare-earth metal that is extremely hard and corrosion-resistant, is commonly used in jewelry as a durable, tarnish-free silvery coating. Being also a good electrical conductor, it is an ideal material for coating electrical connectors. QED’s rhodium plating, applied to the Supremus Zr’s connectors, produces a very smooth surface that maximizes the contact area between the connector and the speaker binding post.
Ultra-low-resistance conductors. The Supremus Zr is QED’s thickest cable to date, measuring 6.2mm2 in cross section. To further improve the already excellent conductivity of the Supremus Zr, QED plates each of the two core conductors with two microns of pure silver. The resulting ultra-low resistance ensures more efficient propagation of the audio signal and allows better control of the speakers.
Aircore technology. According to QED, thick cables like the Supremus Zr are susceptible to what is known as the skin effect, where high frequencies are forced to the outer part of the conductor, where the effective resistance is higher. QED’s Aircore technology reduces the skin effect by employing tubular conductors around a polyethylene core. This is said to equalize resistance across the audioband and to prevent magnetic and electrical interference.
Cryogenic treatment. Cryogenic treatment of metals has been applied to various products, from tools to musical instruments, to improve the microstructure of the material used. Whether cryogenically treating cables has any effect on their sound is a matter of debate, but QED claims that its own subjective testing has confirmed that listeners prefer cryogenically treated cables over non-treated versions, finding them to yield a more natural tonality.
Setup
The QED Supremus Zr cables replaced my Audio Sensibility Statement Single-Wire cables (CA$1099 for a 2m pair). I used my Focal Electra Be II standmount loudspeakers for this audition as well as my Dynaudio Confidence C2 Signature floorstanders. Upstream components included a pair of Bryston 7B3 monoblock amplifiers and a Bryston BR‑20 streaming preamplifier. For most of my listening I streamed from Tidal and Qobuz via Roon, on my Apple Mini M4. For analog playback, I used my Rega P10 turntable, Rega Apheta 3 cartridge, and Gold Note PH‑10 / PSU‑10 phono stage. I used Audio Sensibility Statement interconnects for the Bryston amplifiers and Pangea AC‑9 Mk II power cables.
I did all my listening in my dedicated acoustically treated listening room, which measures 13′W × 18.5′D × 7.75′H.
The gorgeous gold-sheathed Supremus Zr is elegantly packaged in a striking black gatefold box. From the heavy gauge you immediately know this is one serious cable. Despite its thickness, it is surprisingly supple. It does have some spring to it and offers some resistance to twisting, but rolling out my sample pair with moderate curves posed no problem for my open installation. The twist-to-lock banana connectors and cable boots looked as smooth as glass, like polished precious stones. The connectors slipped easily into the binding posts of my amplifiers and speakers, and with a little twist, they readily slipped out. The construction quality of the Supremus Zr, like its materials, is top notch.
Listening
“(Looks Like) Somebody Got Ahead of Schedule on Their Medication” from the Charlie Hunter album Everybody Has a Plan Until They Get Punched in the Mouth (24-bit/96kHz FLAC, GroundUP Music / Qobuz) features an unusual group of instruments: drums, electric bass, and electric guitar, as well as cornet and trombone. It’s a very dynamic, live-sounding recording that packs a real punch, and punch is just what the Supremus Zr cables delivered. The drum thwacks, bass-guitar plucks, and kick-drum strikes had concussive energy. This pounding was tight and articulate, with ample texture in the bass plucks and drumhead snaps. The Supremus Zr cables revealed the warmth of Hunter’s seven-string guitar and the refined shimmer of the cymbal, sustaining it well without compromising the impact of the strikes.
On “400 Lux” from Lorde’s debut album, Pure Heroine (24/192 FLAC, Republic Records / Tidal), the opening synth notes, wrapped in reverb, emerged from just behind the speakers and extended laterally far beyond them to the side walls of my listening room. The deep synth notes were solid and finely textured. Lorde’s bold vocals sounded convincingly natural, and despite the audible sibilance, I remained focused on her singing, paying unusually little attention to the recording quality.
Melody Gardot’s live recording of “Over the Rainbow” from The Essential Melody Gardot (24/96 FLAC, Decca Records / Tidal) is a delicate-sounding, soothing, and intricate track. The gentle opening—featuring acoustic guitar, shakers, percussion, and bird-call effects—made it obvious that the Supremus Zr cables could deliver authentic timbre and texture. The depiction of the instruments was detailed, but not minutely dissected. The presentation was holistic, with each musical element depicted distinctly but as a thread in a musical tapestry. Gardot’s sultry singing voice had an engaging midrange presence and focus.
On “Ponta de Areia” from Esperanza Spalding’s self-titled 2007 album Esperanza (16/44.1 FLAC, Heads Up / Qobuz), the opening bass notes of the large tabla, a traditional Indian drum, pulsed through my room, completely enveloping me. The Supremus Zr cables portrayed this and the other percussion instruments with abundant texture and delightful timbre. The soundstage was expansive and open, and sonic images were sharp and well separated. Spalding’s gentle voice had a vivid presence. Double-bass notes were notably full and textured. The piano had a sweet and authentic tone.
Comparisons
I compared the Supremus Zr cables with my reference cables, the Canadian-made Audio Sensibility Statement Single-Wire. Listening to “Ponta de Areia” with the Audio Sensibility cables, I noticed a slightly more pronounced upper treble that brought out finer details and textures. The Audio Sensibility cables seemed to also reveal a little more of the background reverb. The QED cables sounded smoother and slightly less incisive. Spalding’s voice had greater midrange energy and vividness through the Audio Sensibility cables, while it sounded more relaxed and slightly warmer through the QED cables. The bass was not as weighty with the Audio Sensibility wires and somewhat less articulated compared to the QED cables.
Next, I substituted the considerably cheaper QED Genesis Silver Spiral speaker cables for the Supremus Zr cables. Listening to “Don’t Let Me Drown” by Burna Boy from F1 The Album (16/44.1 FLAC, Atlantic Records / Qobuz), I noticed that the Silver Spiral cables were a little less open than the Supremus Zr cables and less revealing of ambience and reverb. They delivered the backing vocals less distinctly and threw a narrower soundstage. The bass with the Silver Spiral cables was less open and textured than with the Supremus Zr cables, and bass notes had a somewhat vague decay; however, the Silver Spiral cables were surprisingly weightier and fuller. The tonal balance with the Silver Spiral cables appeared to favor the lower frequencies, resulting in a slightly darker, less crisp sound compared to the Supremus Zr cables. Cymbals with the Silver Spiral wires were not as sharply delineated as with the Supremus Zr cables but were still clear. Although similar to the Silver Spiral cables in some respects, the Supremus Zr cables were decidedly more refined, more resolving, and more lifelike.
Conclusion
The QED Signature Supremus Zr cable is a beautiful, superbly constructed speaker cable that delivers an insightful, lifelike presentation without being excessively analytical. Music through the Supremus Zr is engagingly rich but not overripe, with a neutral tonal balance that smooths out the uppermost treble, resulting in a relaxed, fluid, natural sound. This trait makes the Supremus Zr ideal for less-than-ideal recordings. By fully delivering bass weight and dynamics, this cable not only makes for engaging listening experiences, it makes you rock out when the mood strikes. With its resolving capability, neutral tonal balance, and top-end finesse, the QED Supremus Zr is a speaker cable that’s easy to fall in love with.
. . . George de Sa
george@soundstage.com
Associated Equipment:
- Loudspeakers: Dynaudio Confidence C2 Signature, Focal Electra 1008 Be 2
- CD player: Rega Apollo
- Streaming preamplifier: Bryston BR-20
- Amplifiers: Bryston 7B3 monoblocks
- Turntable: Rega P10 with Rega Apheta 3 cartridge
- Phono stage: Gold Note PH-10 / PSU-10
- Music server: Roon Nucleus
- Music Services: Tidal HiFi and Qobuz
- Cables: Audio Sensibility Statement speaker cables, interconnects, and power cables; Pangea AC-9 Mk 2 power cables; Furutech ADL Formula 2 USB cable; Van Damme XLR interconnects
- Network: Netgear wireless modem
QED Signature Supremus Zr loudspeaker cable
Price, as reviewed: US$2700, CA$3499.99, £1799, €1835 for 3m pair; available in 2m, 2.5m, 4m, and 5m lengths for US$2100, US$2400, US$3300, and US$3900, respectively
Warranty: Lifetime
QED Headquarters
Armour Home Electronics
Woodside 2
Dunmow Road
Bishop’s Stortford
Hertsfordshire, UK
CM23 5RG
Website: www.qed.co.uk
