Okay, but I'm not suggesting that spreading DPCs over multiple cores is the only solution. It is a solution in some cases. Originally I was merely responding to your point about not being able to schedule DPCs on other cores. You were speaking more generally from the OS schedulers POV, but I took it more literally.
Honestly.. I've spent countless hours hunting down bad drivers to fix audio stutter and other crap on my gaming PC. I've finally got DPC latency under 10microSec and I'm not touching a thing :)