I'm sure people here have the A800, but that is a roland unit. Cubase is Steinberg and SONAR uses the PC. I'd love to help, but you seem to be sniffing the wrong tree here. I'd try Roland first, then see how Cubase users hook up similar hardware.
Being a PC user and loving a little turn around, I'd like to blame it on the Mac ;-)
Best in search.
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