Idk maybe its a problem with my pair of bt20xs, but comparing to my az09 pro bt20xs sounds way worse and also way bigger and less comfortable. Its like 128kbps mp3 compared to 320kbps. So i am personally not recommend anyone to buy those TRN.
edit:typo
I tried several older Bluetooth adaptors for my flush-mounted 2-pin port earbuds [old KZ models] and I tried the Kbear, the older gray KZ model, and the Bqezyz adaptors [all the kind with wires that hand off your neck] and all were ABSOLUTELY GARBAGE I'm talking loud hissing, channel imbalance, and muddy mids... then I realized that KZ still sold the original AZ09 in the old pin style instead of C-pin and WOW they are sooooooooo good. Almost as good as the much more expensive AZ20.
I want to share my experience with Bluetooth adapters, which I have a few. I have both the KZ AZ09 pro and TRN BT3S PRO and prefer the TRN over the KZ. Not only the TRN one sounds better with aptX-HD, which KZ AZ09 pro does not have (yes, this is the pro model and does not have aptX-HD), also, I found the AZ09 pro kind of a tag heavy or uncomfortable to wear, and felt awkward when pressing the button on the hook. The TRN with the wire on your neck makes it feel lighter to wear, also the volume control is a plus.