I've done a bunch of searching on the forum, but can't find a thread with my exact situation. I recently switched from a head with an aux in to one without. The new one's a Markbass Ninja - absolutely love it. Anyway, I use a drum loop app on my phone to play along with. I used to just plug into the aux in on my old amp, but with the Ninja there isn't one. I've heard that the FX return can be used to plug in an external media source, but when I've tried it, I just get a hiss through the cab. But I am using a stereo 1/8" audio cable with a stereo 1/4" adapter to plug into the FX return. I assume that a proper aux in is stereo and an FX return is mono, so should I just use a patch cord with a 1/4" to 1/8" adapter to connect my phone to the FX return? Would that solve the issue? Is it safe for the amp? Thanks for any advice.