Saffy,
Buy a third Caravelle as the center, get some used totem model ones for the rear they are a reasonable timbre match, sell the Jadis and the Theta David get a solid Pioneer DVD player which will make a nice digital transport and give you a great picture this you can upgrade later., buy a used Meridian Prepro and get an Audio Refinement Multi-5...Finished Build a Parts Express 12" subwoofer for movies and music.
Maybe next year get your tubes back, but for now the family's happy and you're not sufferring. Who know's you may like it better than the Jadis/Theta. I've seen a 568 take out more ambitious equipment than that. Trifield is a new experience so hang out on the Meridian Forum and learn about a new way to listen to 2 channel music. Everyone there was converted so it can happen to you.
Do I have to defend?
If two caravelles are great why not three? The Meridian 568 smokes the theta as a DAC but you'll likely miss the Jadis but for the money the audio refinement is a huge overachiever and I believe will sound great with the Caravelles. I've heard AR Multi-5 run a pair of JM LAbs Alto Utopias and the matching center, and it was good and did not sound grainy or edgy. So I think you'll find it acceptable.
I thought I posted this system originally I'm sorry for the oversite. Like I said in my earlier posts, when you talk to people who cannot get their multi-channel to be better than their two channel. (RSBeck, I own ATC's you own Monitor Audio, who's midfi now?) You end up with a convoluted system and not so good results and clearly more questions. Because there is no focus or commitement to making the most of this investment. Instead its about patching things. Do you want a patched system or an integrated one?
A Meridian/Audio Refinement systems will eclipse the Jadis/Denon system. That Denon isn't that good sounding and the Jadis can't change that.
Gotta let go of the ""HIFI Cred peices" for now and bulk up on the speakers and get a great DAC/prepro. No compromises. Now that you have a multi-channel system make the best of it! Don't sit in denial and and wax nostalgically for the past... make the best of your new system.