What interesting or unusual gear has passed though your system during your audio life?

There are several pieces I regretted but nothing I want back or miss. Even with several bad moves the overall trend has been steady improvement. I still have a few moves left.

I sorely wish I had my 1996 911 Turbo back. I had to sell it because of financial difficulties. 

Good that only batteries at fault. I just recalled I heard the same screech sound a second time, I then put my CJ MV55 into service as replacement, never did go back to NEW. I bet batteries may have been the only problem for guy I sold it to these many years later.
I never did hear the full potential of NEW, it was in one of my early systems, curious as to how it would sound in my present system.
One common misconception about the NEW is that it was Nelson Pass design, it was in fact only Pass influenced design. I purchased mine in 1996, interesting design, and how I learned about how dirty AC affects sound quality. I actually went to in home audio dealer intending to purchase VonSchweikert speakers, came out with NEW.

For me I would say Nestorovic 5As speakers. I had heard them at a dealers once and thought that they were amazing, and years later had the opportunity to buy a beautiful pair for a reasonable price. They were sent to me by the former owner who was a doctor packed terribly in loose boxes wrapped in old rugs, but miraculously were in perfect condition.
I never got them to sound as amazing as they did at the dealers, but they were very special in some ways, and I am happy to have the memory of them and the time I spent with them. 

Interesting to hear Threshold. I guess for me it would be an old Threshold T200 that just wasn't a good sonic match for ML SL3 electrostatic hybrids (out of the room in twenty minutes).     I wish I still had it today, but back then it was worth too much money too keep it and not use it...