The Q has better filtering but with the 3 duets theres better system separation.
Personally I don’t think the Q has better filtering - I think you may have this wrong. In terms of filtering, the Q has 5 IsoZones while the D has 2.
Also:- With x3 Duets you’ll get x3 power cartridges, and there’s some electronics built inside .. definately surge protection; but I vaguely remember reading somewhere that there’s also some filtering taking place in the cartridge. If this is so, then theoretically you should get better filtering AND seperation with x3 Duets.
Further advanges could be physically moving the duets away from each other and/or closer to equipment. But you should also consider costs:- I’ve recently upgraded my whole system to AC12’s, and WOW!! I don’t think you’d want to buy x3 AC12’s just to power up the Duets ...
Finally, you should also consider functionality:- Are you sure you won’t need the additional features of the Q? (power sequencing and 12V trigger).