Bad BT Sound Quality until switched into pairing mode

I have a very strange sound quality issue whwn B50 is in Bluetooth transmission mode.
It can bde connected up too two bluetooth devices as you know.

I have set up two connections :

  1. is for connection with my HAMA Internet Radio
    2, is set up for a another HIFI BT Receiver

Typically i am using 1. or 2. as BT receiver

Sound Source at B50 is optical in.

Strange behaviour:
When B50 is connected in Ransmit mode (steady ble LED) with 1. Device Bluetooth stream quality is very bad.

When B50 is conneted with both Bluetooth transmitters , Sound quality at 1. Device is fine,
Even more strange:

If only 1-st device us conneted (steady blue led) bluetooth stream and sound is very bad, crackling and interupted very often-. When i activate TX pairing mode during active BT connection with device 1, alll is fine. Sound quality is good know. Wonder why and how too fix.

Thanks in advance