Have you considered changing the speakers? Sometimes we get stuck in solving a problem with a component by adding more components...
Just my 5 cents.
Just my 5 cents.
I wouldn't limit myself to Krell. Do some homework and look around. Krell has been having some financial problems lately. Levinson owners went through hell for a couple years when Madrigal was bought out by Harmon International. Same with Aragon owners when Mondial sold out to Klipsch. I'm not saying not to buy Krell, if that's what your heart is set on, but do some homework first.
I ran my Infinity Rennasaince 90's with a KSA200S and the setup worked well. Now I use a FPB300cx. I had issues with the KSA. I also don't recommend shipping that behemoth, as that is how mine got scrapped by FedX comming back from Krell. If your Kappa's are the 9.1's with the bass switch you will need serious power. There is a Infinity Classics web site with a lot of info if your interested. Google it if you want.
Good luck, John
Congrats, that's one of Krell's best amps ever. When you receive it, get the serial number and send it to Krell. Ask them when was the last time the power supply caps were changed. If they have never been changed, I would advise that you have this service done now, since we don't know what lies in the future for Krell.
If driven properly the Kappa 9's are still better than many of todays speakers. They were innovative for their time with the emit and semit drivers. Yes, and unfortunately hard on amplifiers. None the less, still a bargain and very musical from Arnie.
I would not worry about a bad review from TAD as we are all aware that the Kappa 9s are amp eaters. The Krell should be very good at driving a 1 ohm load. I would put the Kappa's against any speakers in the 2K to 7K price range and bet they are able to stand on their own.
You can join the Infinity forum and get a substantial amount of information on the K 9's.
Proud owner of Kappa 9's, RSB 1's, and Genesis 200's
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.