I'm hard pressed to believe this is a budget rig! Then again maybe not as Sony does make one of the nicest DAP's on the market These MH755's could very well be the best bang for the buck iem on the planet (of course one really needs to put even length cables on them)
Trick case and nice control cut out however I believe you've voided your kayak/water sports mode I use my Nanuk with BT DAP's & Waterproff BT speakers during water activities but I do love that clear Pelican and how you can see the MO screen and Mojo lights
Recently acquired the Msr7b. Also use the 99 Classics and Beoplay H6 with either my V40 or Opus#1s. Been listening to the Highway to Hell album a lot this month, to celebrate Bon's birthday, and the 40 year anniversary of the album.
I believe that Han Sound Audio is one of the few that uses it for their Venom cable when it is terminated in 4.4mm. But that one also comes with a parallel 3.5mm (SE) plug for the ground in case the cable is terminated in 2.5mm (ie. the cable has 2 plugs). Of course the 4.4mm terminated cable will only work on a modded WM1Z (or other 4.4mm DAP).