Actualy, I'd question whether demo units are even good enough in conveying the sound sig of a their custom counterparts. I've owned the 335DW for little more than a week now (no impressions yet because I'm waiting for the "new toy syndrome" to die out first), and from what I recall, the demo unit I tried sounded quite different. It wasn't night and day in terms of signature (both were warmish), but the soundstage (or perceived soundstage, as some call it) is very different. The custom-made one conveys far greater depth. Also recall the demo unit presenting the upper bass and lower mids in a slightly more veiled fashion compared to my custom unit, which is clear as crystal at all frequencies.
Strangely, I've struggled with getting good bass response from a lot of demo units I've tried. Fwiw, I was interested in the JH16 at first, since I'm a bit of a basshead. When I got to try the JH Freqphase demo models (13, 16, etc) at a recent show, I found the JH16's bass to be a bit too muddy and laggard compared to what I was used to. Also tried the JH13 and the low frequencies, while cleaner than the JH16, still didn't quite register with me the way I'd like. There seemed to be a complete lack of layering and texture. They told me that it might have been because those were universal demo models and that a custom-made pair would definitely not exhibit those issues. That may well have been true, since many people more experienced with CIEMs rate the JH 13/16 models quite highly, but there was no way I was going to risk spending that much on my first CIEM without knowing what it would truly sound like. Maybe my opinion would have changed if I managed to get hold of Jerry and ask him personally, but he was busy at the time with some other people.
Then I moved to the Fitear booth and tried all their demos. The 335DW was the one that I liked the most (also tried the 334 and 435). There was something about it that was slightly Audeze LCD-like (the old Audeze, before the new characterless Fazor crap) - like a cross between the character of a LCD2 and the detail of a LCD3, but without the veil. Still had some reservations with regards to soundstage, but I was so taken by the 335's sound that it was stuck in my head as I was visiting other booths at the show. Whatever headphone/iem I demo'ed after that, I kept thinking back to the 335. Took it as a sign and decided to put down an order (you can imagine the shock I got when they told me how much a 335 cost) and get my impressions done. Thankfully, the reservations I had about the soundstage and comfort from the demo unit quickly vanished the first day I received the custom pair.
Enjoying the 335DW immensely right now. Hardly listened to my beloved TH900 for the past week. As I said, impressions will come later after the new toy excitement dies down, but I'm very happy with these being my first customs. There's an almost tube-like tone that I hear from them (might be the 000 cable), and that's with them driven straight from my iPhone. Possibly not as much bass as I'd like (remember, I'm a TH900 guy) if you asked me to nit-pick, but it's not so bad and I don't really mind EQ'ing on a portable setup.
Edited by kurochin - 1/16/14 at 9:32am