I have a Schuberth C3 (BMW branded) and Starcom speakers. The space for the speakers in the C3 is cavernous. i do have ears that stick out, so I've been told, and there's no pressure or rubbing at all, and there were no mods that I had to make to the helmet.
It's a pricey piece of kit though - I bought it specifically because it's a super quiet helmet, I don't like earplugs and didn't want to have to wear them.
Ian