Everything about the design of the Sleek SA6 says "custom." They speak of a custom designed single armature driver - as do many other high end IEM manufacturers. Beyond the driver, everything about this Earphone is one-of-a-kind.
The size is small - about the same size as other "small" IEM's from Altec Lansing, Etymotic and others. The smallest IEM I have tested is the Klipsch IMAGE, and the Sleek's are just a bit bigger.
It is the flexibility and custom ability of this IEM that sets it apart. Let's start with the removable cables. Often, the cables are the "weak" link in Earphones. They get caught on things, pulled, tugged and sometimes they snap. When the cable breaks on a $250.00 pair of Earphones - that spells disaster. Not so for the Sleeks. The cable is detachable - it just pops out of the Earphones themselves. If it were to break - just order a new cable which is a fraction of the cost of an entire new set of Earphones.
The Detachable cable also allows for a "swiveling" of the cable. This allows the user to either wear the SA6's with the cable "behind" the ear or just straight down from the ear. Either way is comfortable and secure.
The defining feature of the Sleek design is the "Variable Equalization System." This actually allows the user to "shape" the sound by adding bass ports and treble tips to create a custom sound. Here is an explanation from the Sleek Web Site:
Variable Equalization (VQ) System
The VQ System, or Variable Equalization System, is the first of its kind in an in-ear monitor.
This multi-stage system allows you to completely customize the sound of your music. While you may appreciate brilliant treble, someone else may want deeper bass. Now, with the VQ System, all listening experiences can be tailored: from symphony to hip-hop, or country to rap, everyone can have the sound they love.
First, using Interchangeable High Frequency Filter Tips, the end-user can dramatically alter the sound of the high frequencies to adjust the amount of make up gain they need after inserting sound isolating in-ear monitors. It may be that you like sustained high-frequencies with a peak at the vocals. Or it could be that you want a flat response with some roll off at the upper high end. The choice is yours with our Interchangeable Treble Tips.
Second, low frequency response is a personal preference. Our patent-pending Variable (Interchangeable) Bass Port System maximizes the low-end bass curve. The result is a dramatic 12db difference at 20 hertz between our three interchangeable bass filters, with no effect on the high-frequencies. This is an industry first.
So, when you open your box of Sleek SA6's, what you see is your Earphones and four sets of tiny tubes - these are the "Treble Tips" for adjusting the high frequencies. You also see three small rubber "plugs" that go in the back of the Earphone - these are the "Bass Ports" for increasing or decreasing the Bass output of the Earphone.
I cannot tell you how cool it is to actually adjust the sound of your earphones. This is so much better than an artificial EQ system built into so many MP3 players. I literally swapped out every tip and every port on each ear to try to create the true "custom" sound I desired.
Now, the downside to this system is that these pieces are small and easily misplaced or dropped. Also, the Treble Tips did not always come out easily -sometimes they came out attached to the silicon tip. Jason, From Sleek Audio, assures me that a tool for removing the Treble Tips is in the works.
One added plus for me is that I have a dramatic reduction in high frequency discernment in one of my ears - a result of a blown ear drum and surgery. So, I could actually boost the treble more in that ear - which was a great advantage.
The Sleek SA6's ship with three silicon tips - small medium and large. The medium's were the best fit for me - but my ear size is somewhere between the medium and the small - so I actually swapped out the tips for the medium double flanged silicon tips from my Klipsch earphones and got a better seal. I found myself going back and forth between the Sleek medium tips and other tips. I have read on some enthusiast forums that others are using the foam tips from Shure earphones with the Sleeks as well.
Certainly, comfort is a key quality in an in-ear monitor. The small size and the flexibility of wearing the cable behind the ear or straight down makes for many options to find a comfortable fit. For me, I wore the cable straight down - this was more comfortable. Using the included ear tips (for purposes of this review) was certainly comfortable. They are well designed, seal out a good deal of outside noise and are soft enough to not cause pain in the ear canal.
The small size makes these things weigh next to nothing - which was a good thing.
Another factor in comfort is "fatigue." Earphone fatigue, especially IEM fatigue is an unusual thing. Having all that sound "inside your head" can make people uncomfortable after a prolonged period of time. Some users even complain of "nausea" from prolonged IEM usage.
Thankfully, there was none of that (at least for me or others who tried these out) with the SA6. I really did forget they were there and I was able to focus on the sound - not the fact that things were plugged in my ears.
This is always the make or break issue when it comes to Earphones - and it is always the most subjective part of any review. The "short of it" is that the Sleek SA6 sound great - really great. The long of it is a little more complicated than that.
The "X" factor in the Sleek sound is that you can make it your own. I was skeptical at first of the "VQ" system and how much difference it would really make. The fact is that is does make a difference. If you use an iPod or other music player that plays compressed MP3 files - the difference is noticeable. If you "Amp" your earphones - the difference is astounding.
I tried every combination and permutation of Bass Ports and Treble Tips on the Sleeks. The Treble Tips are in a nice foam array with a cardboard cutout that says "=,""+" or "-." "=" is for neutral treble sound, "+" gives the High end a boost and "-" reduces the Treble.
I first listened to the "=" Tip and found the Treble pleasing - but somewhat lacking. The high end was certainly clear and sharp - but not as brilliant as other Earphones I had listened to. The "-" Tips seemed to suck the life right out of my music - so those ones got the boot right away. When I put on the "+" tip the high end was magical - clear, not sibilant, sharp, bright - but not too bright. Vocals, cymbals and instrumentals began to soar.
In new packages of Sleek SA6's, they are also including a "++" Tip for even brighter high end. When I used the "++" tip, I found the highs to be too "bright" for my liking.
Like the Treble Tips, I tried all the Bass Port combinations. The "=" Ports allowed for smooth, if somewhat anemic sounding bass. I could certainly still hear the drums and bass guitar - but I certainly could not "feel" them. The "-" Port seemed to swallow up not only the bass, but also the midrange. The "+" Port gave me the best bass experience. I could hear the "punch" of the Bass Drum and I could hear every not of the lower end - but, I still did not "feel" the bass like I did with the Klipsch IMAGE. I found myself wishing for a "++" Bass Port.
It is hard for me to describe this completely - but the Sleek SA6 might just be the most "musical" IEM I have very listened to. The sound was "fun." It wasn't particularly "warm" and it wasn't overly "lively" it was fun and musical. Part of that certainly has to do with the Sound Stage of the SA6. The sound does not come from "inside your head" as it does on other IEMs - it is as close to wearing good "over the ear" earphones in terms of sound stage as I have experience with a Canal Phone or IEM. The sounds comes from everywhere - the musicians were truly surrounding me and I was enveloped in great musical sound quality. This is one of those things that needs to be experienced to be truly appreciated.
Vocals were "pure" on the SA6 - they really sounded the way (I think) they were intended. The only exception were vocals that had more bass in the voice. I did many "head to head" comparisons with other Earphones and mostly did close comparisons with the Klipsch IMAGE. For Vocals like James Taylor, Cat Stevens, Elton John, Lyle Lovett, Sheryl Crow, Josh Groban and the like - the Sleek's provides the best vocals I have heard in an IEM. For Bruce Springsteen, Norah Jones, Joe Cocker, Ray Charles and the like - the IMAGE provided a more full vocal experience.
For Instrumental music - especially guitar and piano - the Sleeks were "dead on." Beautiful reproduction and presence.
For most "Rock" - the Sleeks fell a little short of the IMAGE - mostly due to the reduced bass response.
For Jazz - the Sleeks were tremendous - all the highs of the symbols and the horns and a beautiful midrange coupled with the great sound stage made these a winner.