The H6 offers Mic and Line inputs. If your effects chain ends up at Line level you can connect it directly. If it ends up at "guitar" level, you'll need to run it through something that makes it look like a Line or Mic source first.
"All four main H6 inputs (inputs 1-4) are combo connectors that can accept either XLR or ¼” balanced or unbalanced phone cables. They can handle both mic- and line-level signals, which means that you can connect either external microphones or line-level devices like mixers, portable music players, electronic keyboards, or electric guitars or basses with active electronics (passive electric guitars or basses can also be connected with the use of a mixer or effects device)."