Hi.
I just wanted to explain Hugo's question. For some reason, some empegs/riocars are set do -indefinite dB (no sound at all) on first start. My MkII wasn't, my MkIIa was and the MkIIa (from the same batch as mine) wasn't. No idea why.
Anyway, with your RioCar set to 0dB, you should get sound out of your empeg.
To me, this sounds like a problem for
support@empeg.com, 'cause you really should get some sound out of it. You already ruled out cable and amplifier issues, so this seems to be a defect of the riocar itself. You should really contact support.
cu,
sven