Congrats on the new H90! Lots of possibilities when combining two of them.
This really depends on what you want to achieve. Using H90 2 in the insert loop of H90 1 will give you many routing options since you can place H90 2 at various point of the signal path. You could also place it in parallel, which would be more difficult to setup if you aren’t using the insert path of H90 1.
I would say using H90 1 as the dedicated looper and then using H90 2 for the additional effects in the insert loop would provide the greatest amount of flexibility.
