When I connect to bluetooth on my iPod I only get sound out of the two front speakers.
You need to go into the settings and change the BT HF/Audio from the default front speakers setting to the All speakers setting. The default factory setting is FRONT, so it needs to be changed.
This procedure can be found on the owner’s manual.
Make sure that the unit is in STANDBY mode when you go into the settings, otherwise the option may not appear