The "e" upgrade improves the sound quality of the K-5x noticeably. Whether or not this will result in sound that you like is only something you can say. As always, the best way to know is to try it for yourself in your own system.
In another post you noted that the Nagra preamp also lacked "warmth" and "body" in your system. I don't have direct experience with the Nagra, but the fact that it is a tube-type preamp would suggest that there is something else in your system that is causing the lack of "warmth" and "body".
In these situations, I normally look first to the tweaks and fine-tuning rather than the components themselves. It is important to make sure that the AC polarity of each of your components is correct. I believe that you are in Germany (Schuko plugs), so this is much easier than in the US.
Floating the units (disconnecting the AC mains ground) also can result in significant improvements in sound quality. (Ayre equipment made in the last several years does not require floating, as there is no connection to the AC mains ground.) However, please note that floating the ground connection can increase the risk of an electrical hazard in certain very rare situations. Do this step at your own risk.
Use of wood blocks as supports under all of your components (except loudspeakers) is highly recommended. Also use wood blocks under all cables, interconnects, and power cords that may be resting on the floor. This is especially important if your floor is carpeted.
Soundstage depth is usually improved via speaker placement. Check the Cardas web site for instructions on how to use the Golden Ratio to place your speakers.
Finally, many cables can cause the symptoms you have described. It may be worthwhile to try different interconnects, speaker cables, and power cords in your system.
