i will soon get my HX Stomp but i already know how i will use it. i also own a scarlett 2i2 but it's not my main audio input. I use a software named VoiceMeter Banana as mixer and i can manage several inputs like my micorphone/headset, my scarlett, my audio from computer and all of this mixing it or not in a final "output", then this output (the mixed signal) can be used anywhere Daw etc. I love this solution that is costless because the software is free and you can manage what you want and send all signals where you want. I will probably manage directly the HX stomp in this software. This solution also helps for other purpose as streaming or things like that or directly track and record something while you are playing on a youtube backing track.
Well voicemetter is not very easy to anderstand and setup but there is plenty of tutorials out there :)
For mac user there is soundFLower that is the equivalent of voicemeeter banana :)
there is no right solution but plenty of solutions :) also you can plug both output in your focusrite. and use both in daw for multitracking etc :)