I have previously bought this Bluetooth tranceiver, but ultimately it didn’t work well. In fact, it died. I suspect it was due to charging the battery while it is in use at the same time.
Well, i now got my hands on a Bluetooth 5 transceiver. It runs on the Qualcomm CSR8675 chip, which is probably the market leader. I ordered a pair so that i can be assured of the most reliable wireless audio transmission possible, but alas, the seller only shipped one unit, and refunded me the payment for the second unit. I will probably have to order another one next time.
Anyhow, i tried pairing this lone Bluetooth 5 transmitter with the built-in Bluetooth receiver on my mixer, and the result was fantastic! The audio quality was really spectacular, despite the Bluetooth receiver on my mixer being at most Bluetooth 4.1 (it is unspecified).
I tried using the Bluetooth transmitter while charging it at the same time and it resulted in some high pitched noise. I guess it is generally not a good idea to do so, the circuitry might be damaged.
I highly recommend this Bluetooth transmitter/receiver. If you need SPDIF input/output, you can get the bigger box and it cost only 20 Yuan more.