What are you hooking up? I'm guessing the FX processor goes between the instrument and the amplifier. Not likely that you'll blow up anything. Chord from the instrument to a line in on the FX. Line out from the FX to a line in on the amp.

Are your line 1/4" plugs or are they XLR (1/2" metal sleave with three prongs on one end, three holes on the other)

Why the slitter? Are you trying to run two instruments through one FX channel? This may work but I don't believe it will be really effective.

Good luck.

Don