Congratulations on your new H90! The answer to your question depends on how clean you run your amp. If you do not rely on its preamp section for overdrive or distortion, then you can plug the pedalbalrd straight into the amp. However, any hint of break up, and I recommend what you suggested, to put your gain-based effects in the front and the time-based effects in the back. The easiest way to do that is to run the H90 in dual routing mode, which you can switch in the System Menu. Path 1 can be connected to the front of the amp and Path 2 to the effects loop. The QuickStart guide that came with the pedal has a diagram showing you how to do this.
