Want to share my experience comparing the Levinson and the Pass. I was a long-time Thiel user (15+ years). I started this hobby with a pair of Thiel 2.2s, then upgraded to a pair of 3.6s. I had paired the 3.6s with the Levinson 333 for 8 years and thought it was a good combo. During that time, the caps in the Levinson blew up on me several times. I finally traded in for a Pass X350.5.
At that point in time, I had been contemplating about upgrading my speakers to Thiel 6 for two years. I was under the impression that with my setup, I had pushed the 3.6s to it's "limit". The sound I got was as good as I could get out of the 3.6s. When I inserted the Pass, not-yet-broken-in, into the system, I could not believe the vast improvement over the Levinson that I was hearing. The bass was deeper and more solid, more extension at the top, and the soundstage was wider/deeper, but more 3-dimensional. At that point, I was seriously reconsidering to keep my speakers. But then, where's the fun. I ended up selling them 3 months later. I didn't get the Thiel 6 as originally planned, but a pair of Verity Parsifal Encores.
I invited a friend, who was very familiar with my system, over that first week, just to make sure I wasn't fooling myself. He went home after the listening session and put his Levinson 432 on Audigon and bought a Pass X350.5 too.
FrankC