First question I have is am I just daisy chaining the second h9 into the midi circuit?

Also how are you guys connecting the inputs and outputs? I do use a second amp (a fender Princeton 68) from the L output of my es8. To be honest I’m not overly technical and did get myself in a bit of a muddle previously trying to use the 2 inputs and 2 outputs on my h9 and setting up pre and post etc. Kind of want to keep it simple but what would the benefits of a stereo set up be? 

1. Yes. You would want to set the MIDI output mode of the first H9 to thru. And set the MIDI Channel of the first H9 to 1 and second H9 to 2. So you can control two H9 independently with ES-8.

2. If you need stereo effect, then 2 amps are definitely better (For example, if you want different delay time or different pitches on two amps). The simplest way to do it is putting the first H9 to Send/Return 7 and the second H9 to Send/Return 8, and connect ES-8's LR outputs to two amps. By doing so you can use 2 H9s stereo effects. PRE/POST mode would sacrifice H9's stereo effect. So if you use PRE/POST mode on an H9, this H9 can only make mono effects.