Initial impressions of the audio quality are very encouraging as the single driver design gives a warm smooth sound that is very enjoyable. They lack the high-end accuracy that gives classical and acoustic music that open airiness that feels so intimate but rock and pop is dealt will brilliantly, especially as the volume is cranked up. Many reports cite the SA6s as having a flat sound - i.e. not exaggerated bass - but to my Shure accustomed ears they do sound distinctly more bass heavy. Overall, straight out of the box they remind me of the Klipsch Image set that Riyad just recently reviewed, which can now be had for about the same price as these.
Of course the straight out of the box sound is only one part of the SA6s arsenal and by switching between all the different treble and bass ports, you can get closer to the sound that you prefer. That said, the differences are not abundantly obvious particularly with regards the bass ports. The three different bass ports are supposed to span a range of 12db at the 20 hertz point, with an accompanying drop off around that frequency. Testing by listening to, surely the perfect test tune, 20Hz by Capricorn (a classical Trance tune) the differences are highlighted but overall the affect is subtle.
The difference between the various treble ports is more apparent and choosing the ++ ports really brings out the sibilants and cymbals. Personally I never actually settled on one particular setup, though, as all of them sounded decent and yet none really changed the overall quality of the tone - that is they don't add extra thumping bass or add that aforementioned high-end clarity. Think of it as you would tweaking the performance of a car - you can stiffen the suspension and change the intercooler but nothing's going to make your sporty hatchback into a supercar. Not to say that these earphones aren't supercars of sorts in the first place but you get the drift.