Hmm, I saw your image #3 that says "topping internal clock" and said WTF? Then I looked up Topping D10s and see that it's a DDC as well as a DAC. I doubt it but, if the D10s shows up as a 4 or more channel USB input, your (elegant) solution would be to chain the Schiit to the Topping using SPDIF out of the D10s DDC feature and skip the aggregate device. Since that's probably not possible, I'd go back to first principles by making sure you can send audio to each DAC separately (without static) and then recreating the aggregate device with the Schiit set for drift correction.
This is above my pay grade but, I believe as a DDC, it has to be the clock master (which doesn't apply to USB) so you may be SOL using the Topping in an aggregate. In otherwords, the D10s might not be a DAC that can be used in an aggregate device. Any way you can beg/borrow another DAC to try instead of the Topping? Otherwise, sorry, I'm out of ideas and maybe someone else can chime in.