Would adding a Dac improve the sound for my setup?

I just replace my signalcable with My Audio Cable Paradise power cord costing only $200 which connects wall to the conditioner for my cd player. The improvement is immediate and I'm sure a better conditioner will improve the soundstage. Having said that I still think room treatment will yield the most improvement in soundstage.

Thanks everyone for the comment.
Ckoffend, it is exactly what you described. Large scale or complicated music would diminish soundstage while small scale is great.

Ok then I'll give priority to room treatment. Unfortunately I can only treat the front wall behind the speakers, because this is in our master bedroom. My wife doesn't want to see too many things. I'll put a artistic panel behind each speaker and start from there.