As many Krells had switchable mains voltages inside, I have not found any info on this KSA300S for you. The best is to send and email to Krell and ask.
"Is it easy for a technician to convert a Krell KSA300 from 110v-115v to 230-240v without having to buy new mains transformers"
This way you'll find out if it's a simple transformer primary wiring change.
Cheers George