You're certainly dealing with two incredible products there, Chris.
Others can talk about the potential interaction with the SoundLabs speakers if they are what you are pairing them with. The only thing I can really add is that cabling and the room (most importnatly) are definitely going to figure into things, and a bit of tube rolling may prove enough to change your mind.
I'm not sure what tubes you ran in the JA200, but the DA88S uses KT88, which I find dark/recessed in the mids compared to EL34 tubes. In my experience, Jadis amps sound their best, by far, with EL34 tubes, though you then have to be far more careful in terms of getting the driver tubes right in order to produce the proper low frequency response, which the Jadis are more than capable of.
Peter, did you hear the JA500 with and without the Da Hong modifications? Removing it from my DA60 made all of the difference in the world in my situation. Others have corresponded with me over the years to echo that sentiment. In fact, it was the on the recommendation of a friend that I had my amp set back to "stock", and I can't thank him enough for the performance that wrought.
