Which ARC reference component to upgrade?


I have the ARC Reference 3 preamp and Reference 110 amp and am considering an upgrade in the ARC line. I can't do both right now. The question is, which change (Ref 3 to Ref 5SE; Ref 110 to Ref 150) would result in the best improvement in my system?

System:
Ref 3
Ref 110
Wilson Sophia 2
Music Server to Berkeley Alpha Dac 1
Esoteric X01
FMS Nexus cables
mmcghee
I would suggest a power conditioner for all your stuff, except the amp, as the next step 'up'.
I have a Furman REF20i
You might check out that or others..
I recently upgraded my Densen B-250 to the B-250+ and submit, besides changing speakers, I heard the most significant improvements I've ever heard. I'm not talking night and day, but significant. I've read many comments about how the preamp has more impact on the sound than any other component...based on my experience I agree and suggest starting with the preamp.
What is your current system not doing that you would want your upgraded system to do?