Hi babydickonboard welcome to MDCF forums! As A440 said R700 should record in stereo just like mine. If you still can't record in stereo perhaps is time for you to return the unit to your friend and get a new one.
My car stereo don't have the AUX in so I used cassette adopter but is noisy. I bought an FM transmitter but the quality is so bad. I went to car stereo shop for hard wire and it works! Now with this method no more annoying noise, good quality and no worries about batteries.
I just bought my Nano a silicone cover and screen protector to protect from scratch but you know what I'm still using most of the time my 3 MDs, RH910 for recording, NHF800 in my car, and R700 in my bed. Don't ask me why.
Are you a bass guitar player? just curious GM, do you have any idea what low frequency used in early models with megabass (bass 1, bass 2)? It sounds like lower than 100Hz.