I am currently evaluating a pair of loaner Sleek SA6 and Klipsch Image X10, and so far the Image are hands down better in the bass and treble department, while they are closer to being equals in the mids. As a matter of fact, with some music I'm finding the SA6 to be a bit bland and dull, because they seem to lack extension in the highs and lows (a bit rolled off to me).
With iMod and portable Vcap dock, I am having trouble picking an amp that wakes up the SA6 enough for me, whether with Bass+/Treble++ or any other bass ports and treble tips. I am finding the SA6 are better amped, but still not what I am looking for.
However, I can NOT make the Image sound bad with any of the portable amps in my user profile. The Image are even acceptable through iPod 5.5G headphone out, and are as enjoyable to listen to as any of my custom IEM.
Now, I am not saying the SA6 are bad, but neither am I impressed. They are good enough that I would put them on the level of my previous q-JAYS, (but with less bass), but not good enough to want a pair of my own. The SA6 are detailed, and neutral, with little coloration, are fairly forward in the mids and soundstage, and are not prone to sibilance. But they lack the transparency that I get from all my customs or the Klipsch Image, despite the forward mids of the Klispch (which are helped when amped by the Pico).