What one change to your room, system, or setup made the biggest improvement?

@thecarpathian 

funny,

That damn tonearm came with a bad wire, had to have VAS re-wire it, so I put the old wire in the photo to remind me.

I found that toothbrush on Amazon, I love the tall bristles that let you stay further away, and wood not plastic (unavailable)

https://www.amazon.com/dp/B0CQC1TN25?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1

search is so easy these days

Here it seems to be (I paid less than this)

https://helixsounds.com/products/turntable-stylus-brush-cleaner

need black or plastic

https://www.groovewasher.com/products/groovewasher-stylus-brush

better price

https://www.ebay.com/itm/115390515612?itmmeta=01KS05CV2KX73WY8EPXXA5N0ZN&hash=item1addcf899c:g:QEAAAOSws7die952&itmprp=enc%3AAQALAAAA4DKQclQvzFwZQpmMrsO4LupvlyyTTKNiD48FkiCGGYo4ZavbKoEOTc8RMt5Vlw4GuqLl8M3tjyeFgB21sz4SopEC9SRLwzJBWIJF9VpCVSwAD%2FRKnJSs0GPZKtBaUOxVr6BE%2BbhB4za5wAKrM28Tpy%2B%2BMoef%2FCn2SaAzWeCe%2BD6YpPyzkUUhOj%2FyLK3FOSW2w40Lr1EZ%2BCf30wEaqS2M%2BsxfNMn3TepeHZFtivS8MJUB4J%2BkKcP8RnD8hVBgFjwlPYUb0Qoy%2FY8ULXDd97XOyJO4NwWKyYHVmgMH2MPFyhdO%7Ctkp%3ABk9SR7Kxs4XIZw

Speaker placement

Most recent was replacing the Alpha USB with Denefrips Gaia.  I had no expectations and was truly surprised at the dramatic improvement.  Afterall 1s are 1s.  

Because the room is 50% of the sound: bass traps and first reflection diffusion.

Room treatments made a significant difference but over the years moving up to progressively better speakers have made the most difference. Putting Sonus Faber in my system was a big improvement. I went up the SF line to reference level and it was a significant improvement, to the point I thought I was done. About a year ago, I went to Zellaton speakers and the improvement was astonishing. Retained what I loved about SF but improved speed, bass, and a more natural tone, to my ears. All of which confirms my view that the room and loudspeakers are the most meaningful considerations in system building, but there are many different opinions on that point.