I don't think you'll have any quality loss sending the CD through the Empeg's Aux-in. Theoretically, if the EQ is flat and the Empeg is set to 0db, it should sound no different than if you'd plugged the CD straight into your amp. (In theory... right?)

I think the worst possible thing is that you might induce a ground loop, and your installer can take care of that if it happens.

Isn't that what you're doing with the portable right now? Have you had problems with its sound quality and that's why you're talking about doing this?

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Tony Fabris