Monkey, don't know if this makes a difference or not but I've come to attribute a somewhat "hot" top end on the 13Pro's as not quite getting a proper seal. That would also account for the sense of lacking bass. I noticed the "hot" treble mostly with the demo's but when I first got my 13Pro's I wasn't sure what to make of the sound, I expected if I wasn't getting a good seal they would sound like ass but they sounded pretty good albeit the bass seemed a bit shy from my recollections of them. Now, after one refit, I'm able to get a much better seal and the sound quality has increased quite a bit, bass is noticeably more solid and they seem smoother and more spacious on a whole.