Not used it as described above, but thought of using it as an amp between a bluetooth module and an Autocom unit, so emailed Gary (producer of Amplirider) nad his response was-
"The amp should work well in this application, since it has a 3-pole stereo input and output jack. It would create a boost in the volume from the GPS and then send it into the Autocom system so you could hear things easier."
And being powered from the bike, it should give a better output than the Fiio E06, also got a volume control...