Bluetooth Dongle?

[Onemanband]

It was suggested that here was the best place for help/advice.

I have recently purchased a Switchcraft 318BT Bluetooth dongle for playing home made drum/bass tracks behind my guitar /vocals, through my Soundcraft efx8 mixer (powering the dongle phantom power@ 48v).
The (Bluetooth/Mixer) pairing is totally silent but as soon as any streaming commences, drum trax or mp3 music trax (or even test radio streaming), a horrible low frequency static rumble persists behind the playing track creating totally unacceptable background noise. Track ends, streaming stops, pairing is silent again!

I have tested this with various devices (Samsung, Apple, Huawei), all with the same result.

I have also tested my device(s) directly through my JBL Eon One and Bose S1 that both have "built in" Bluetooth connectivity; both are noise free.

It appears then that the problem lies within the Switchcraft dongle and/or the 48v phantom power supplying it.
It is possible to power the dongle independently with a 5v usb supply; not much quieter and it defeats my objective of being cable free.

Anyone else had similar issues with Bluetooth or this particular Switchcraft product? Any advice greatly appreciated.

Thank you....Brian.