I would strongly advise against using a preamp with your unit, it has a preamp built in, and a very good one at that. In my view there is no sense in adding another gain stage, with its consequent losses due to interconnects, circuitry, etc. If you can bypass the Orchestra's preamp stage (does it have a pre-in input?), you might be able to do it, I guess, but unless you're going to use something of the caliber of a JP80MC or a Lamm L2 why bother? Just my 2 cents.
Preamp for Jadis Orchestra Ref
I have a Jadis Orchestra Reference amplifier. I have read in threads sometime ago (must be over a year) that a preamp would improve it's sound. I tried to look for the old threads but they seem to have been deleted (not sure if it was this site or elsewhere). I listen to everything (rock, alternative, acoustic, female vocals, jazz, classical) and the amp does a decent job with all. I have it hooked to a pair of Cabasse Farellas. I am wondering if anyone has had experience matching a preamp to this integrated.