I want to be able to run 2 amps in stereo coming from a stereo effects pedal - like my timeline. To eliminate ground loops, I picked up a behringer hum destroyer (HD400) used for $10. It works great - BUT, it doesn't have the ability to switch the phase on the amps. I've seen a number of ABY boxes that have phase reverse, but that isn't exactly what I want. I want to have stereo in - stereo out with a phase reverse. I'm sure there are some, but I don't know what they are... I know I can just play with speaker cable polarity, but I often have to rely on backline, where it would be much more of a pain trying to trouble shoot on the fly, rather than simply having something on my board that could quickly flip the phase on one of the amps.