active or passive?

You need a nice tube preamp to add some human quality to the music reproduction.

Listening is usually the correct solution to such a question. Unfortunately, it's not always possible unless you live in an area with many high end dealers. The first limitation is that passive preamps do not work well with sources that have a low output level.

You can use a passive preamp when you have a buffer like an active cross-over IMHO. Otherwise you loose dynamics.

Passive preamp in most cases will not suffice for KSA.

Marakanetz, interesting answer, mine works great with my ksa-250. The ksa-150 is even better match. What did you base your answer on?