Thanks for your kind comments. Frankly, the Quad ESL 63s were simply far superior to the Apogees. The Centaurus Minors I had were good sounding speakers for the money. The Quads are simply in a different league.
Regarding the big changes - many factors.
1. Long ago I was able to compare my Naim 72 preamp to a First Sound passive preamp. I was amazed at how much more transparent the First Sound was. The Naim was rolled off at the frequency extremes. In spite of that, I live contentedly for several decades gradually upgrading through the Naim hierarchy. But I felt there was more out there beyond Naim. The Innersound Electrostatic amplifier I bought a little while after I got my ESL63s showed me the limitations of the Naim 135s. The Naims were good. The Innersound was simply better. Clearer. More performance-transparent. :^)
@toro3 Thanks man. You appear to be a person of extreme sensitivity, keen perception and fine judgement! Wish we could share a cup of coffee and listen to to some tunes. ;>)
@joel_hifi
Thanks, also for your comments. Yes, I switch between the two systems at will. Neither is perfect but each has something to offer. Regarding the impact of the filled Expedit shelves on the sound... I'm not really sure. I've probably got about 55 inches between the back of the Quads and the shelves. And the shelves are, I think, 15 inches deep. And I listen primarily in the near field.
@jmalen123 Thanks man. I appreciate your comments.
@robert53 Thank you.
@jond Thanks man. You are kind.
You are all so kind to check out my system. Hope you are having a great holiday.