3 Models to Choose From
ZCable sells the standard 8-layered Z-Sleeve v1 for $99 each. The Ref1 model's 26 layers will set you back $199/ea, while the Ultra1 and its 36 layers of isolation come at a cost of $299/ea. I was sent enough of each of the v1s and Ultras to do my entire system.

Typically I would place a single Z-sleeve over the interconnect at a component's input. I used them on the S/PDIF coaxial connection between CD player and DAC, between DAC and preamp and between preamp and power amp. I also used the sleeves over the power cords at the IEC input at the back of the amps. Typically I also found that two sleeves right at the speaker's inputs worked quite well.

Z-Sleeve v1
The 24-hour settling-in period ZCable claims is a fact. At least twice during my time with the sleeves did I place them in the system only to forget them. Upon initial insertion, you don't hear much if any difference so I'd walk away from the system and not give the specific configuration and use any further thought. Twice I would return to the system the next day to hear something distinctly wrong. Both times I heard what I can only describe as a silvery sheen over the music. Not a brightening per se but a slight hash overlaying the music to obscure warmth, detail and throwing off instrumental timbres while veiling harmonic body. Both times I discovered that I had forgotten to first remove the Audio Magic Stealth from the system. You see, where the Z-Sleeves are concerned, you can indeed have too much of a good thing. I could use my power conditioner or the Z-Sleeves but not both. The first such incident happened the very first time I introduced the Z-Sleeves to my system. It was proof positive that the sleeves were indeed doing something other than wishful thinking.

Getting to know exactly what the Z-Sleeves were doing was a long and evolutionary task. In their longer-than-usual stay here, I've used them in what amounts to many different contexts while many different speakers and amplifiers came and went. With each change came new revelations. When the Z-Sleeves first arrived, I was in the middle of evaluating the marvelous Duevel Bella Luna Diamante loudspeakers. When distributor Ted Lindblad left, he was concerned over an upper midrange edge that we both heard and had been unable to alleviate through cable swapping. Once back home, Ted went as far as packing up several interconnects and speaker wires that he was sure would do the trick so he sent them along. Alas, it was only after I'd installed the standard Z-Sleeves (well, actually about 24 hours later), that I was able to smooth out the Duevels. It was the exact same story with the Thiel CS 2.4s. Were it not for the Z-Sleeves, my review description of both speakers' upper midrange would have had to include words like edgy and brittle.

Female vocalists were the main beneficiaries here. Prior to the sleeves, both speakers exhibited an unwanted edge on Sara McLachlan's Fumbling Toward Ecstasy [Arista 18725-2 07822]. This CD is recorded on the slightly hot side and tracks such as "Ice Cream" can push speakers with a forward upper midrange right over the edge. Ditto for Jennifer Warren's Famous Blue Raincoat [Private Music 01005-82092-2], which also suffers an inconsistent upper midrange prominence. From time to time, her voice can sound positively screechy. The Z-Sleeves didn't change the timbre of her voice but noticeably tamed the surrounding sizzle. Changes in instrumental rightness were slightly less apparent but were observable and appreciated nevertheless.

The massed violins from Paganini's "Moto Perpetuo" on Rostropovich, Return to Russia [Sony Classical SK 45836] came across with an added measure of both purity and body, likely due to the removal of a slight electronic hash that one would never otherwise know to be present, or else blame on the recording. It was much the same for "Malaguena" from DMP's Carved In Stone [CD-512], a collection of Big Band numbers. The opening brass came across with a slightly reduced sense of glare and a heightened sense of purity. Again, both of these effects were subtle but important.

With less forward speakers such as the Silverlines and Magnepans, I didn't notice quite as much of a change through the upper midrange region. There was no unwanted sweetening per se but I did observe a notable and welcome increase of focus, particularly on female vocals and strings, and a slightly smoother rendering overall. Particularly on the Silverline Boleros I heard the music take on an added air of refinement throughout the treble. Credit, I suppose, must go to the excellent Dynaudio Esotar tweeter with its high resolution and over-the-top extension for showcasing the Z-Sleeves effect in this region. It sounded notably cleaner, slightly smoother and evidenced a small yet important gain in palpability with the Z-Sleeves in place. In my system and my room, I can't say that I heard any effect of the standard Z-Sleeves on bass or lower to mid vocal range performance whatsoever. But as no two rooms are likely to suffer the same types and degrees of aural pollutants, I won't claim that my observation would mirror yours. Likely, your mileage will vary. Why do I say that? Because I've yet to touch on the Ultra1 sleeves. They proved that a lot of the sleeve's performance comes down to matters of degree - or layers of protection.