I've been using a wm2000 shanling neck band that sounded good my T4 iems. I did get an OE angled adapter, tried it after my RME Babyface Pro, the magic was totally gone. This morning I tried a moondrop click dongle that I had, was bright and bass extension was lacking so it was super shouty and percussive. I want to get something worthy of the MK2 next month so I just ordered a ddHiFi - TC44Pro USB-C to 4.4mm Adapter, should be a good step up from the "click", if it's good enough I might just put off getting a good one for a while.
How was the HD800s? I can't imagine it to be a huge tonal shift from the HD800, but I've never heard it.
With the MK2 I did order a set of AZLA SednaEarfit MAX Eartips For TWS, they were good but I think I preferred the bass response with the stock foam (small), I've got the a SpinFit - W1 in the mail, I wonder if they are similar to the CP100 you mentioned.
How different does the UTWS5 sound compared to the BTR5 or Quidelix-5k? I'm still researching my next move for an on the go solution. My current android only does ACC, my older phone is still working fine with the LDAC hi-rez and has a headphone jack! I should audition that phone for dap duties.
Though I think a DAP might be the way to go for an endgame solution for me, I find my M1 ultra stutter/jitter even without the switcher. The RME sounds good, can't imagine what a real audiophile dac/amp would sound like, I thought the HD800 was good but honestly I have a plexi and 4x12 behind me, guitars always sounded terrible on the HD800. And now the contrast with the MK2 couldn't be further. It's still great for movies etc but I'd be interested to see if they get a new lease of life with a proper modern DAP or DAC/Amp. Fun times amids a miserable world atm