Balanced...Sonic Frontiers and Audio Research are both good matches with your amp. Many other tube pre's would also sound fantastic but your need for balanced will keep your list somewhat small.
I use a single-ended tube pre with my Ksa-250 and am very happy with this blend of SS and tube sound in my system.
Dave
I use a single-ended tube pre with my Ksa-250 and am very happy with this blend of SS and tube sound in my system.
Dave