is there a sat nav that does an ear piece so you can hear wot its teling you like what you have for a mobile phone blue tooth thingy ?
i have tom tom 6 on my pda ,this has a socket for an earpiece.wired not bluetooth though hope that helps
Only way i have heard of is doing a “BIKER” that is
getting one set of ear phones and cutting jack plug off then drilling a small hole to feed earphone cable into back of sat nav,the just solder the wire onto the speaker connections
the other way is to do the wire soldering bit but the use a female connection at the other end so you just plug in your earphones.
either way works but invalidates warrenty
have a look at the tomtom rider as it comes with a bluetooth headset
there is also the garmin zumo not sure if this comes with a bt headset ot not
I use a TomTomrider + earpiece (bluetooth), I likes it.
my navman has a socket for a earpiece