This applies to Leaf (DG50), C51, DG60, DG80 and C81
Using your own headphone/headset with an Avantree USB adapter but unhappy with the Voice-Chat sound quality. That is because the headphone doesn't support Faststream codec.
FastStream is a type of Bluetooth codec, all the Avantree USB adapters mentioned above supports FastStream. When you connect a headphone/headset that supports FastStream to the adapter, you'll be able to get 16-bit Stereo Quality voice chats - much better than the Mono quality you've been getting through your own headphones.
FastStream Headphones we recommend: Aria, AH6B, Aria Pro, NB16.
Or if you use Avantree C81 on PS4/PS5, you could use the 3.5mm mic which is coming with C81 to get the stereo sound quality while talking- How to use the 3.5mm microphone？
Please feel free to contact us at firstname.lastname@example.org if you're still not sure.