The way you take a balanced out and run into into a common-ground input is to use some form of converter.
Cheap converters are passive and use transformers. They usually have HORRIBLE frequency response curves, and they are usually designed for speaker-level signals, not preamp-level signals, so their internal attenuation will reduce the preamp voltage, and ruin your signal-to-noise ratio. Also, the transformers LOVE to pick up EMI out of the air and give you MORE noise.
I would include just about any passive converter made in this list. I don't know how the Jensen Transformers (different from Jensen car audio) ISO-MAX would work, but I have used it in other applications and it has worked great.
Your better bet would be to use a device with differential inputs and RCA outputs.
You can use any line driver with balanced inputs such as an Arc Audio.
You can use any Audio Control processor.
You could use a 360 from Rockford but it is way overkill unless you plan on using lots of processing options.
Use a Zapco I-Force. They are not $800.