The iDEA was always an (pardon the pun) interesting idea.
However in practice I always found the MP3 loading, recording ,selecting files somewhat akward.

The iDEA guitar (and the preamp upgrade kit) includes a aux in.
I found a Bluetooth receiver that can be used to bring in my iPhone media (read backing tracks).
The BT rechargeable receiver is very small and can be plugged into the aux jack and paired with phone.

The iDEA setting is in Guitar AUX, in record mode.
The headphones and the guitar cord jack combine the backing tracks and the guitar when playing.

I am using this:
Amazon.com: HVMLAK Bluetooth Aux Adapter
ASIN B0C6MBGQ7K Item model number HVM-BTR005

For my use I have moved the aux jack up near the pre amp area to keep it from sticking out around the guitar cable jack.