Any recommendations for a good 4.4mm copper cable ?
I have very good experience with the Sony Kimber balanced cable (the MUC-M12SB1). I first tried it on the Westone UMPro30, and it impressed me sufficiently that I got another 3 (!) for all my IEMS with the MMCX connector - the Pinnacle P1, the Campfire Audio Jupiter, the AK T8ie Mk II & the Sony XBA-A3. All demonstrated audible improvements from the cable, to varying degrees. The sound became deliciously meaty, with deeper bass response and better imaging (to my ears).
Now, I have no idea if the improvements come from the balanced connection or the cables - I have no other 4.4mm cable to compare against. I got them from Jaben Malaysia. They were probably the cheapest place in the world to get the Sony cables - RM398 or about USD90 for one. I kinda suspected that it was a pricing error, because that was way, way, way below the MSRP. I talked to some local retailers and they were not happy about Jaben Malaysia's advertised price lol. Maybe someone complained to Sony - It probably explains why they are no longer offered for sale (the page listing on the site returns a page not found error).