Telenav GPS, Bluetooth and Treo 750

[KBLACWELL]

I was told by a Telenav customer service rep yesterday that it is not possible to have the Telenav GPS unit paired with a blue tooth headset and the treo 750 so as to have the audio directions come in over the headset rather than the speakers on the treo. I found that rather lame because that means with the low volume on the treo you have to switch the radio off to even barely hear the directions. What's the use of a GPS unit if you can hear your turns clearly or you have to give something else up to use it.
Anybody ever hear of such a thing?