Krell processor up grade for audio stereo .

I have a HT system with Krell Showcase processor and would like to up grade for a better audio (stereo only).
I'm considering three options for the pre amp:
- up grade to another processor as Krell S1000;
- keep the Showcase and add the preamp Krell KAV 280p connected to the processor;
- keep the Showcase and add a top preamp as Krell Evolution 222 or similar;
I'm also considering to buy a high end CD player and change the interconnect cables to XLR.
The amps are Krell 2 x KAV 2250 (front) and KAV 3250 (surround). The front speakers are BW 803.

Is there really a considerable difference for audio stereo among these theree options ?
I also had the Showcase and the 803Ds. upgrading to the Evo222 made a slight but worthwhile difference. However, upgrading the speakers made a much larger and better difference...spend the money on better speakers.
I had the showcase and kav 2250 on 803s and then upgraded to the hts 7.1. Quite a difference for stereo. The HTS 7.1 is definitely known for it's analog bypass, and with a good source it can really shine. It really is far ahead of the showcase and is dirt cheap used.
not to complicate things but i was just doing some experimenting with my krell amps on saturday. i use the 3250 for my surrounds as well and krell fpb600c for fronts. i wanted to see how the 3250 would sound on the fronts and oh my, it was a huge step down. i did not think an amp change between krells would sound so different but it certainly did. so my suggestion would be the amp and if you like the krell sound, there are allot of older fpb's for pretty good $'s now. they are a bit inconvenient but, imo of course, sound so much better than the kav series.
i am selling my 3250 after that experience. best of luck and enjoy the music...