I’ve heard No. 334 and X150.5 in the same system for a few hours when a friend was trying to decide to replace his 334 with the Pass unit. At the end we both agreed we liked the No. 334 better so he decided to keep it. His had gone through a major (and expensive) service which included new capacitors and a couple of other electronics a few months before the comparison. I must add the sound after the service got dramatically better so an unmolested unit may not sound much better than the X150.5. The Levinson just sounded fuller with more uniform sound top to bottom. By comparison the Pass sounded a bit disjointed across the frequency range with some frequency ranges sounding more forward and others relatively more recessed. Don’t know how to describe it any better.