I talked to a DAW hardware specialist from scan.co.uk.
- All DAWs he knows, treat multi core realtime processing basically in the same way.
- A single channel and all it’s subsequent routing is always handled in a single thread by a single core (so single core performance and speed are the bottleneck if you have channels with demanding VSTis or VST FX).
- If your project’s load is less concentrated on (few) channels with very demanding plug-ins but rather has a big channel count, then you will benefit from having more cores, since all the different tracks can be handled in separate threads and thereby be assigned to different cores.
This generally applies to realtime processing in Audio. Non-realtime applications such as 3D rendering are different and the single core performance is less important.
There are also articles on processor choise in the Steinberg Knowledge base and in the Ableton online help to support this.