If the Orchestra can drive your speakers to your satisfaction I assume the MV-55 will probably not be overly stressed. It ultimately depends on your room size, what you listen to, and how loudly. I used my MV-55 in a smallish apartment with my Thiel 2.2's, and it gave me all that the room (and my neighbors) could handle, even playing power rock music. But when I moved to a larger space in a single family house, it was underpowered and began to distort when playing solo acoustic piano at naturally realistic levels (I replaced it with 200w monoblocks). Don't specifically know about the combo of the SF's and the CJ (or how the CJ sounds compared to the Jadis), but the MV-55's output transformers are designed to work well into a 4 ohm load. This is a very pleasant-to-listen-to amp overall, just don't expect world-beating transparency, resolution, neutrality, extension, dynamic nuance/contrast, spaciousness, or control. I found the SED EL-34's to work best among current production types.
