HelloI have had my Khorns for about 10 yrs and have tried a fair amount of gear with them....I currently use BOTH tube and SS.
The better the amp, the better they sound REGARDLESS of watts....true they need very little to get going, right now for ss I am using
a Mac c46/mac252 and it sounds great.
I also have a Linn wakonda/lk100 also sounds very nice thru the Khorns.
For tube gear I use a VTL 2.5/st85(with triode switching) sounds great.for the money..VTL and K horns are a great match, I have also used the VTL IT85 also a great match.
The other combo I have used is a Mac C2200/restored Dynaco ST70...what a killer combo..damn if the Dynaco doesn't sound good...and its a bargain.
It seems in tubes the K horns fly with el34s.
Back to the original question, you may want to try a Mac 6500 int amp or the 6900 both fine units