Dave these di's are normal, they sound like an average, run-of-the-mill di to me (other than the panning issue), that I've recorded hundreds just like it, if not a thousand of 'em...
The panning
will be an issue for re-amping. Just to make it short, the amp will only be getting half the signal. I know this myself from my experiences. With my setup, I have to have my di track panned to the center, & the fader at "0", or the amp will not get the full di signal it's supposed to. I use hardware output 4 in Reaper for my routing, & my RMP box's signal is just a little lower than plugging straight into the amp, so I bump the signal via the hardware send in Reaper...
The problems the op is having aren't with his cables (other than him having the di output going back into the interface...

), interface or hardware, it's software/daw, & user error related. It's a routing issue. His amp will only be getting half the signal it's supposed to with the KA6 because he doesn't have all his inputs/outputs enabled in his daw. On top of that, he's running his di signal back into itself from the re-amp box back into the interface, when it should be going to the input of his amp instead...
I don't think he's actually getting any tone loss, other than the fact he's running his interface/re-amp box in a big loop, basically running the di signal back into itself. I have no idea why he's trying to do this, when he should have the 1/4" cable coming from the RMP going to his amp, with a mic set up to record into the KA6.
Signal chain should be:
Guitar > interface > re-amp box > amp > mic > daw
The op is gonna have to read up on how to set up his inputs/outputs in Sonar with the KA6. I'm assuming Sonar is like Cubase sorta, just for shits-n-giggles a couple months ago, I tried this myself (Cubase LE5), & while it's not very intuitive (to me anyway), it can be done. This is a big reason I stick with Reaper, it's just very easy & simple to use...