Krell HTS preamp upgrade

Does anyone know if it is possible to upgrade my Krell Home Theater Standard 5.1 to 7 channel?
Very unlikely but only Krell can say with certainty.

Ditto on that. You should ask Krell for a definitive answer. Have you tried them already with no answer or the like?
I don't know of a Krell forum but given the popularity of their products it seems like there ought to be one.