I'm planning a little project to turn my HD25-1 II and HD 668B balanced. For the cables I'm planning to use SPC 28 AWG, but the connectors I'm having a bit of a harder time with.
I'm thinking of terminating my HD25-1 II's balanced connection with a TRRS connector instead of a 4-pin XLR to reduce bulk for portable use. To connect to an iPhone and other unbalanced sources, the two negatives can be rerouted to a common ground to turn the entire setup back to unbalanced via a TRRS-to-TRS adapter cable. At home, where I have a balanced source audio interface, I can use a breakout cable from the TRRS to give a dual TRS balanced connection.
But durability also has to play a role, and for that 1/4 connectors are very tough while keeping a slim, in-line profile with the cable. I can find plenty of 3.5mm TRRS connectors around, probably because they're popular with headphones that have an in-line mic, but none that I can find are 1/4", let alone a gold-plated one. Is there a reason why this is the case, or am I just not searching hard enough?
Also, is there any loss in sound quality in playing balanced audio through 3.5mm balanced TRS/TRRS vs. 1/4" balanced TRS/TRRS vs. a 4-pin XLR plug?