gakertyDefinitely can’t be a impedance issue, your Rouge is 200kohm input and only needs 1v in to for full power out, no problem going direct
I’ve run my ADI-2 directly into my poweramp (Rogue ST100) and it sounded good, albeit a bit drier and less full
I think dryer tighter is a good thing, maybe just need a re-tune speaker position a little closer to the back wall maybe, system/room/interconnects.
Also did you stay with the 4ohm taps on the ST100? Because the 8ohm now maybe fuller richer and far more powerful also.
Cheers George