Behringer UFX1604 and UFX1204 unneeded implicit feedback

Hello Takashi and everyone,

Behringer UFX1204 and UFX1604 have sync endpoints and we set up implicit feedback sync on them. This is against the UAC spec. We've already fixed a major source of noise by explictly setting up the Clock Selector. Therefore in my humble opinion we should now disable implicit feedback sync for those two devices.

What do you think?

Thank you, Geraldo Nascimento