i have a Sena 20s and also use a sena transmitter unit ,cant remember the unit number.
i use an adapter cable that goes from headset cable to sena sm 10 that is the unit I could not remember.
useing the sena 20s and sm10 I can listen to any source on bike and also gps.
the sm10also allows all this to transmit to two headsets so your passenger can also listen.
Hope all this makes since to you..
How in Gods name can you hear directions coming through the speakers at any speed.