www.reamp.com this explains the history of the problem and provides a solution.
The solution is patented. I believe the Radial Xamp is a legally liscensed reamp box. I like Radial stuff, and I believe the steel boxes they use give better protection against magnetic hum fields than aluminium boxes.
There are a few other reamp boxes, which somehow get around the patent issue - possibly by compromising something. I'm not a fan of lot's of unnecessary switches in a signal path, so the little boxes that can switch between DI and reamp aren't my cup of tea.