Thanks for the recommendation, I really am looking for a bluetooth device, I usually use the BTR5 in bluetooth about 80% of the time using APTX and APTX-HD - and about 20-30% of the time as a USB-DAC.You are better off upgrading your DAC. You will get better sound and it won't be that much more than the adapters you are looking at. And, the adapters attenuate the sound and lose connectivity over time.
I would look at any of the following depending on your preferred use case:
Ifi Go Blu: Get this if you want Bluetooth
Lotoo PAW S2, L&P W2, Cayin RU6 is money is not an issue and you want the best sound
Lotoo PAW S1 used if money is an issue. You can get one for around $100.
Ifi Go BLU seem ok - maybe I'll get a W2 as a secondary device and check it out, I'm curious to compare it to the BTR5 - which is a good device IMO - I listened yesterday several FLAC albums for about 5 hours with the BTR5 connected via USB-DAC and wow my brain was blown away with instrumental - rock - electronic music. Great soundstage, and layering of instruments. MEST are really great IEM's.
All the best,
Rizzoli