Made a head-fi account just for this thread basically. Just wanted to leave some thoughts here.
I've used the UTWS 3 previously and upgraded to the 5 recently. They sound great, though I am not even close to getting full potential out of them, as my Pixel 6 Pro supports neither aptx Adaptive nor LHDC (I've been considering getting a cheap Chinese phone just for music lately..).
I still want to mention how grateful I am for this kind of product, and for the FiiO employees that are around to listen to user feedback and answer questions. Probably the reason I made this account, so I can engage in some of the conversation on here.
Also, I've got a few adapters from AliExpress to help me connect two of my favorites, and I wanted to leave some pictures here to maybe help some others with their IEM setup.
For my Katos, I've got angled 2 Pin adapters, which I even prefer over the OE Audio angled adapters, because the angle is a little less aggressive and the adapters have pretty much the exact same thinkness as the arms of the UTWS5. For anyone using 2 pin IEMs without recessed sockets (Moondrop Variations for example), the adapters should also be available in a shorter variant.
Now, I've seen someone asking about compatibility with IE900s, and for those there's a great pair of adapters aswell. I went for the straight ones in that case, because the angle of the connectors on the IE3/6/900s is already pretty steep.
Both adapters result in a great fit for my ears and I can recommend both of them!
I also really hope LDAC will be an option in the (not so near) future (probably?), I love my Pixel but the bluetooth codecs are pretty basic, and I find myself longing for higher quality audio via LDAC or aptX HD, both of which are supported on my BTR3K, but that is way less convenient.