I own the BE20Ds and have heard the older Viennas at RMAF about 5 years ago. Asuming the new Viennas like the Musik sound similar to 5 years back they are revealing and true to the source, and very slightly on the warm side. The Ushers with the stock xovers are much more forgiving and warmer sounding. I can't speaker for the Viennas in terms of amp requirements but the Ushers, while ~90DB and about a 4-5 ohm load nominal really wake up with good higher power SS amps. My dealer had stated they match well with Pass Labs amps and from a power providing standpoint, I agree. I have mine bi - amped with a dedicated 250W / ch MF amp on the woofers, they truly came alive. An option if you are willing and able would be to upgrade the Ushers' crossovers which changed their tonality (much less warm, significant detail retrieval + the woofers respond much faster being crossed over at ~200 rather than ~400Hz). GR Research is who I used for the xovers, highly recommended as the owner / designer Danny Richie designed crossovers for Usher and many other mfrs. If you are anywhere near the Austin area feel free to come by and hear mine. In the end, only you can decide and I highly recommend driving or flying to hear options especially when spending 5 figures. I hope this helps.