Use one of your analog inputs on the H8000FW making sure you have the output of the H8000FW going into your daw (I go analog in on H8000FW to Adat out to Adat in on Motu 2408mk3) at 96khz.
Then run from your analog synth a high resonant sound and slowly sweep the freq just around your hearing threshold.
I noticed a mirroring aliasing effect in the spectrogram which is audibly present. Does not do it at 44khz at all only 96khz (not tried 88khz yet). No dsp was in the chain i.e just straight analog in to digital out. Only use 96khz because plugins sound nicer to me (Nebula plugin runs lovely at 96khz) and also the H8000FW is a bit sweeter on the fx.
Have tried to get my rather inferior is sound Motu 2408mk3 to alias but can not. Have emailed a full description to the team, not sure there is a fix for me if it is just my unit as I have just recently had mine back from USA and the shipping to UK killed me lol.