James - This is a favorite of mine from a music perspective…just stellar frozen a time stuff with coconspirators I love… I have the 50 th and a pristine German PP. i find the 50 th to have a layer of grunge and murk removed. As you know i am a level matching dude and from the get go the 50 th is cut a whisker hotter, tredle clear, extended and sweet. i expect this would sound awesome on your ESL 63. Tamalpais High has wall to wall soundscapes. I believe both Joel and Steve also have the 50 th.
IMO very much worth having.
Jim