Performance

I am very fond of the old Sleek-Audio SA6 design and have been enjoying those in-ears for quite a while. The configuration that suits my needs the best is with the bass “plus” port and treble “plus” tube. So I had my custom Sleeks made to the same specification so the only differences in sound between the two should be down to the difference in materials and the fact that the customs do not have a silicone tip, that to some extent does alter the sound.

The custom Sleeks are a very different design compared to its universal styled cousin the SA6s so just because they are made to sound alike does not mean they will perform identically. The acoustic properties of the materials and the shape can affect the sound quality greatly. The Sleek-Audio Customs are a single balanced armature design so nothing has changed there since the original SA6s. The in-ears I will be comparing the Sleek-Audio Customs in-ears to are the following: LiveWires T1 Custom earphones, Sleek-Audio SA6, Yuin OK1 earbuds. I used the same rig to compare the earphones, which consists of my Cowon D2 DAP hooked up to a Ray Samuels Audio Tomahawk earphone amplifier.

Like the old Sleek-Audio SA6 earphones the new custom ones are medium sensitive for a pair of earphones which is alright because it means that they do not hiss as much when using them on a noisy source.

Surprisingly enough the custom Sleek earphones with supposedly the same configuration as the SA6s sound quite a bit different. One of the noticeable differences is that the mids and highs are a wee bit more dominant and that it has a more liquid, airy quality to the sound. The SA6s are anything but muddy, but in comparison to what the custom version offers they are clearly out shined in when it comes to smoothness and detail. The midrange bears some resemblance to that of the SA6 when it comes to intensity, but it is a little more refined and gives you are a more smooth sound which is quite nice. It still carries the same detail, it just sounds a wee bit more natural, this could be because of the coloration the SA6s get from the silicone tip. The bass is pretty much the same, it is a little tighter and extends a little lower on the custom Sleeks.

The midrange is really the Sleek-Audio custom earphones' strongest side. It is smooth, neutral, and very detailed with a great sense of ambiance. Compared to custom earphones such as the LiveWires the midrange of the Sleek-Audio ones are much more forward in the mix, taking a much more dominant role in the music, bringing forward instruments such as guitars, and vocals. The LiveWires' primary focus is bass, and while it does that nicely some would probably argue it was a bit too dominant. The Sleek-Audio custom in-ears strike me as having a lot more neutral sound with less bass and more mids and highs. Bass extension still is about the same as that of the LiveWires, but it is less intense. The bass lacks the full powerful sound of the LiveWires, but that said, it is far from the worst bass performer I have heard. If you are looking for a pair of basshead in-ears, the Sleek-Audio ones will probably leave you wanting more. They simply cannot deliver the slam like what I heard from the LiveWires, however, if you are biased towards a more neutral frequency response you should definitely have a look at the Sleeks. For rock I found the Sleeks to have about the right amount of bass, and they are more analytical in their presentation than the LiveWires.

The high end is just about perfect, it has a good amount of sparkle without sounding harsh or sibilant on normal records. The treble extension is the best I have heard in a long while and the definition is incredible, leaps ahead of the LiveWires in that respect. The great part about it is that you can customize the earphones to sound the way you want them. If the treble tuning works just as good as exchanging treble tubes on the SA6s you can trim it to your needs right from low treble to sparkly. I had mine built with the treble plus tuning, because I enjoy a sparkly presentation of music with a bit above average treble energy, and the Sleek-Audio Custom in-ears provide just that. The treble is really refined delivering oodles of details and it has just the right level in order to be an integral part of the sound without being overly dominant or tiring to listen to, due to sibilance. On just about any track with half-decent mastering the treble is just where I want it, but on some lousy recordings it is a bit shill, but that is not the earphone's fault. The sound stage is pretty good for set of in-ears, it is quite wide but lacks depth. Left to right separation and space is quite good, reminds me a lot of my LiveWires. You get a real sense of layering in the music from the Sleeks even in the busy parts of a recording, to a much greater extent than on say a pair of SA6s or LiveWires for that matter. Sound stage is still nowhere near what you can get from a pair of Yuin OK1s, but that is almost an apples to oranges comparison due to the fact that the OK1s only function well as earbuds.

Like the SA6 earphones the custom Sleeks have the same cable which means that they have the same characteristics when it comes to microphonics. The disturbance is very little with the cable worn over the ear. Only the LiveWires are less effected by microphonic noise than the Sleeks but they also feature a much softer more volatile cable with an extremely soft coating on.

Noise attenuation wise these block out just as much noise as my other in-ears no noticeable difference here.

Durability

The Sleek-Audio Custom in-ears are really durable. The hard acyclic shell will withstand normal wear and tear easily. All the joints between the acyclic shell pieces seem well bonded together and are almost invisible. If you carry the earphones around in the box they ship in they will be impossible to break unless you use a nuke, but then your DAP will most likely be fried. The cable is of a good quality and so are both the male coaxial plugs and the mini plug on the end. However, do not expect miracles it is still a thin cable with a minimum number of protective layers in order to keep the weight and microphonics down.