Hello,
I own the Helicon 400s and just went through a number of cable swaps. The end result is I felt the Dali's are VERY cable sensetive. I loved the mids and highs with Audioquest Gibraltars but the bass was "boomey". I tried a double run of DH labs T-14 for fun and low and behold the bass was tight, accurate, and abundant. Not boomey at all. However the mids backed off a bit. To me the Dali's mids are recessed a bit anyway so, the DH labs would not work. I wound up bi-wiring DH labs on bottom and Gibraltar on top. I works very well for me. I have not heard the Viennas. I'm sure you will be happy either way you go.
I own the Helicon 400s and just went through a number of cable swaps. The end result is I felt the Dali's are VERY cable sensetive. I loved the mids and highs with Audioquest Gibraltars but the bass was "boomey". I tried a double run of DH labs T-14 for fun and low and behold the bass was tight, accurate, and abundant. Not boomey at all. However the mids backed off a bit. To me the Dali's mids are recessed a bit anyway so, the DH labs would not work. I wound up bi-wiring DH labs on bottom and Gibraltar on top. I works very well for me. I have not heard the Viennas. I'm sure you will be happy either way you go.