montana 700i amps mount audio tones

[5fl]

hi,700i in a powered amps mount, i have been trying for ages to get the internal tones to work while in the mount.spoke to garmin support uk today and they say the amps mount speaker cable overrides the tones menu option for internal beeps,this i find hard to beleive as my 610 used to beep in its mount.i have tried every setting i can find but still no turn by turn beeps or waypoint arrival beeps,only if i connect earphones to the cable i get audio. HELP (running latest 23.10)