Is there any reason you couldn’t expand the concept of the Pre/Post routing with “Linked” and “Toggle” options?
For example, for a given preset, “Linked” would mean that when the H9 effect is engaged, the effect passes through the H9 and FX loop but when you bypass the H9 it bypasses the loop as well (straight from Input 1 into Output 2)? For “Toggle” it would be the opposite. When the H9 is bypassed it is routed through the FX loop, but when the H9 is engaged the FX loop is bypassed. Obviously you would also have a “Normal” option for how the H9 functions right now. These three choices (Normal, Linked, Toggle) would only be a second layer of options that you have if the pre/post feature is enabled, and all three would each work with pre or post.
