The overall performance is, in my opinion, outstanding. Improvements were noticed in nearly every category of audio description....specifically I noticed the largest improvements in: musical clarity, soundstage depth and width, imaging focus, detail in bass, mid, and trebel, and the kicker is that these make my beloved old CDs which are mostly lower quality recordings sound quite enjoyable! These are very effective line conditioners, and do their job without limiting dynamics in the least.

The weight of these babies can be problematic, especially if you have no rack. Ideally the sleeves are to be placed nearest the component that the cable is leading to....so if you don't have a rack you may have to keep the sleeve further down the cable than is ideal. I don't know how much, or even if this will degrade performance.

Aesthetics....having a large-ish tube hung by string behind your component rack may not look nice....but boy does it sound nice.

Price is high, but so is the performance. Prior to purchase I wasn't sure if this would work out to a good price / performance ratio, but afterwards, I am convinced it does...I've just placed my second order, so I put my '$$ is where my mouth is'.

As far as sonic weaknesses, I can not come up with a single one.

My review is of the Extra Heavy Z-Sleeve, not the Ref1.

Let me start by stating 2 things. 1) My system is primarily mid-fi. (Anthem AVM20, Anthem MCA50, Denon 2900, B&W CDM-9nt & matching center and rears, Kimber BifocalXL, Kimber Hero ICs, Walker SST, VH Audio Pulsar ICs, VH Audio power cords, Vibrapods+cones, DIY room lenses(Jon Risch), Monster 3500 mkII, Paradigm servo 15, M&K MX150, DIY cable lifters, etc...) 2) I live about 400-meters from a radio transmission array that obviously injects all sorts of RFI (radio frequency interference) into my power lines, ICs, and speaker cables....thus I live in an area of very high EMI/RFI. Anyone living in a cityor near industrial complexes has similar EMI/RFI pollution problem....this review pertains especially to you.

My system is (was?) a bit bright, and hard to listen to on especially poor recordings (almonst all of my older CDs fit in this category). I've been considering new line conditioners, speakers, amps or preamps to help rectify the harshness/brightness. Well, after doing some talking with Ric Schultz (www.tweakaudio.com, great guy! He's also a Z-Cable dealer) he convinced me that some Z-sleeves might just do the trick and would cost less than most of the components I was considering. Z-Cable also offers a 30-day money back guarantee on all of their products, so what do I have to lose?

After talking with Ric, I communicated briefly with Mark Hampton (Z-Cable owner/founder) and I found out that yes, 2 ICs (left and right) can be put through one sleeve with a degradation in performance of about 30%. Also, if a single IC is long enough, it can be passed through a single Sleeve twice (looped around) and will provide significant improvement. Mark also letme know that wrapping the sleeve and the looped/exposed portion of the IC in heavy tinfoil can improve the performance yet once again. He also let me know that these sleeves have an effect immediately, but it can take 20-40-hrs for the cables to fully acclimate and reach their full potential

At this point I bucked-up and purchased 4-Extra Heavy Sleeves. These things are HEAVY. I used the provided cotton string to attach these to my rack and then inserted the appropriate analog interconnect through each sleeve (L&R into amp, from pre and L&R into pre from CD/DVD). The sleeves are directional, so follow the arrow on the labeling on the sleeve. I booted up my system and for the first 5-min I wasn't sure if I was hearing much.....but after about 10-minutes (for lack of better expression) I was lifting my jaw off of the floor!!!! "Is this really my system?", I asked myself. Holy Cow!!! I can hear into the music so much deeper...so much better. The harshness and brightness are totally gone and I still have the immediacy and detail that I love...sweet, sweet detail. Notes decay like nothing I've ever experienced, all from a dead quiet backbround, and my system has become so natural sounding its freaky. This is the most impressive tweak I've tried. Heck, its better than any component upgrade I've made.... The most comparable upgrade (in subjective perceptable perfomance improvement) that I've done was upgrading from Rat Shak speaker cable to the Kimber BifocalXLs! That's a VERY hefty jump in performance (and $$$). The next best was the Walker SST (Super Silver Treatment).....and in my opinion, and in my system the 4 Z-Sleeves match and/or exceed the performance improvements that either of these tweak/upgrades made.

I have not tried them on my speaker cables yet, but I will soon. Nor have I tried them on power cords or digital ICs, all of which are purported to respond just as favorably as the analog ICs. They also work well on phono cables, according to John Potis' review on www.6moons.com.

I like them sooo much I have just given up on upgrading my components and have spent the remainder of the money I saved for speakers on 5-more of these Extra Heavy Sleeves. I just placed the order this morning. They are that good!

I would heartily reccomend these to everyone (low-fi, mid-fi, and hi-fi), especially since they have a 30-day money back guarantee!

Customer Service

Very nice. I talked with 2 dealers and the company owner/founder. All were friendly, infomative, and responsive. Each and every one of them got back to me in the same day that I contacted them....that's pretty darn good in my opinion.

Similar Products Used:

There is nothing similar to a Z-Sleeve, PERIOD. Regardless, I have used various ferrite rings with limited success. I tried a monster 3500mkII power conditioner which works but it severely limits dynamics / transient attack.