speakers for creek 5350se?

What are your desires in the upgrade ? Bottom end or transparency / resolution ? In my experience going for transparency / resolution AND great depth/bottom end in a single package means big $$$$. That's why I recently added a REL strata sub to my Densen / Spica Angelus combination. The spicas have a lovely mid/treble, but couldn't drive the low end. The combination is fantastic ... I'd say better than the Kef 103s which a friend has.

If it's mainly for transparency then the AE1s (mentioned above) are very good, and proacs might work well. Also try out Epos if you can find them. I've always liked Epos, but never heard them with Creek. However the companies are closely tied now, so I wouldn't be surprised if the products work well together. Then there's always the Spendor 3/5. (Sorry for my obvious Brit bias ... it's what I am most familiar with, being a Brit myself).

Totem speakers work very well with Creek. I heard a 5350 driving the Totem forest and it was very good. I am currently driving Totem Arros with a Creek 4330 using Nordost Blue Heaven spkr and ic's and it is very sweet and I will be upgrading to a 5350 very soon primarily to get a better remote switiching.

I suggest you go to Vandersteen 2ce signature. The 1C's are already quite a good match. 2ce will give you near full range sound that will make orchestra real. the minimonitors will get you this. I would also stay with Audioquest. I have gone back and forth to kimber and AQ.
primarily between AQ emerald to Kimber select copper.
Main difference of AQ to Kimber:
AQ, much better bass and drive, but upper mid can be a bit forward
Kimber, nice upper mid and highs, but softer low bass and lack mid bass.
Vandersteen would definitely match better with AQ.

Good luck

Sorry...just think you have it all ass-backwards! Find a speaker you LOVE IN YOUR ROOM, and then see if the Creek drives it well. If so...you're done. If not, get other amplification. Speaker/room loading is by far the most critical aspect of your system. The proper amp simply enables it.... Good luck.