I was in a similar situation. I did upgrade my interconnects from WBC and Cardas Clear. There was a bit of improvement in the stage width and pinpointing of instruments/singers. I am not certain it was worth the money, but I am not going back.
Regarding the DAC, that could very well make the biggest difference. I looked at the DAVE, as well as the Tambaqui, Weiss, and others. I selected the Bricasti M1S2 due to the options it provides. When I want clear and clinical like the Dave, it does that really well. If I want some minimal adjustments, it has several filter options for that. I expect the M1S2 is my endgame DAC.
Another DAC I would recommend is the LTA aero DAC. I have the LTA preamp and absolutely love it. While I have not heard the Aero, the reviews are very positive. LTA has a nice try it at home guarantee as well.
Enjoy the search!