Having been thinking a bit about the design decision with the IE800 to use a large 2.5mm TRS joint at the Y-Split on these.
I had the pleasure of listening to a presentation Axel Grell gave on the design philosophy of the HD800 at a UK Head-Fi meet last year, and despite my having some issues with the HD800, I could not help but admire the level of innovation and problem solving that went into every single aspect of the headphone’s design. I don’t think there is a centimetre of that headphone that is not exactly as it is for a specific reason to achieve some performance improvement and I have to believe the same is the case with Grell’s IE800.
I have speculated long and hard as to the design decision and have three contending theories, maybe all three are true, more likely none are, but I thought I'd share:
1. 1. Grell and his team identified some performance issue with the break in the cable being so close to the driver.
2. 2. They identified a performance issue with the small size of such connectors. Typically these have to be made or plated with a non-oxidising metal that is less conductive, like gold or nickel, and as they are so small on IEMs this could present some issues. If they did find that the tiny connectors of these cables knocked performance, that would certainly explain the use of the large 2.5mm TRS at the Y-Split.
3. 3. The driver may be extremely sensitive to changes in the resistance and material the cable is made of. Maybe Grell, knowing that audiophile types like to mess around with custom cables, decided to ensure that the last stretch of cable going to the driver was always going to be that of his choosing in order to stop people changing the character of the sound with their own cable.
If anyone has any other suggestions, answers on a postcard.