I think everything above the CK3000 has line level output.
Actually, the CK3000 does too (I think) but you have to splice into the wiring before the parrot's amp.
All the newer kits have the amp and relay's built in to the brain box, so that is why they offer a line level output.
I actually think I am going to upgrade to the MK6100. I put one in my wife's pilot, and I like it alot better. The ring tone is an actual ring, instead of the evolutions stupid little beep. And everything is done via the screen instead of evolutions audible prompts (from the bitch with French accent

)
If I do, I am going to try sending the line level into the bose amp, and get a new phone that has a2dp, and see how it sounds streaming mp3 audio.