Why n ot, if input impedance of Krell not a mismatch with output impedance of BAT? I use a tube pre with my 300cx very happily. There is an internal adjustment that you are supposed to make on the amp but I have heard of many who do not bother and have no problem with tube pres. Check Krell manual or email them.
It is a terrific amp. I have had mine for more than 6 years without a day of trouble.
Neal