Many years back I drove a pair of Kappa 8's with a Krell KSA-50 MKii. It was incredible. A 50 watt per amp driving the impossible to drive Kappa speakers.
That amp did a great job of owning the low frequency drivers, and had a wonderful presence in the uppers. After a full night of listening I wondered how that amp did not catch fire, but the harder it was driven the better it performed.
The Kapa 9's of course will need at a minimum a KSA-100. My advise is to look for an older KSA-100 MKii where the air vents up out the top of the unit. These would have been made perhaps 1987-1989.
Many people knock the older fan units, I think that this series of amps has the lush warm sound of a tube, mixed with an incredible dynamic low end control.
It really comes down to simple maintenance, keep the amps off the floor, blow the dust out of the unit at least annually, and enjoy. If the pervious owner did not do this, then you may need a new pair of fans, but simple maintenance will make them last noise free for the next 20 years.
You have no idea how good those Kapa's are until you drive them with an older Krell.
Enjoy!