Having heard both recently and they are great options in the $2k range. elow is my opinion - please take it with a grain of salt without getting offended:
Build Quality - Both are excellent.
Music Performance (Full Range) - Mids and highs were equally good. I dont think anyone stood out there. The Ascend Tower took the cake because it was able to play deeper and more dynamic without compression. They both perform (and measure well).
Music Performance (with Sub) - Salk Song Tower won here because the sub could fill in for the bass. the upper treble battle.
Movies - Ascend Tower shined no question. Perhaps due to its dedicated woofer for mids and higher sensitivity. Played loud and clear.
Design - From a aesthetic and designer point of view, the Tower looked very clean. I thought the Salk Tower looked like a sideways MTM speaker stamped on a wood rectangle (no offense). To counter that comment, Salk has many customer and beautiful wood working that can be done for an extra fee.
Overall - I would choose the Ascend Tower for its ability to multitask between HT and Music. There were no real glaring downsides for my application. The icing is that Ascend's Horizon Center absolutely blows away the Song Center in every aspect. Crucial for HT applications.
Professional Reviews of both here:http://www.enjoythemusic.com/magazin..._songtower.htmhttp://www.enjoythemusic.com/magazin...er_speaker.htm