i owned -4- Adona ’Zero’ GXT racks for the last 12 years in my ’no-holds-barred’ system. you can see pictures on my system page.
here is the model i had. two of mine were 4 shelf, and two were 3 shelf. i sold them for 60% of what retail was when i bought them after 12 years. i experienced zero rack issues for that 12 years. the Zero GXT model has a very large and high mass top shelf ideal for turntables. which was the big attraction for me.
https://www.adonacorporation.com/zerogxt.html
in December 2023 i switched to Massif Audio Racks, which are all wood, mostly for cosmetics.
i highly recommend the Adona racks. high value solid racks. can’t comment on the lower level models, but the GXT level is very well made. but it’s not a decoupling rack. it’s meant to provide a very solid base to add your own shelf tuning/decoupling treatments. i really liked the Granite/wood shelves....high mass and very solid. Adona is modular, so you can move things around, and break them down for shipping too. i had good experiences dealing with Adona. they always followed thru with things.
high quality decoupling racks are very expensive and can be very difficult to sell or ship if you want to change. i prefer treating each component myself to investing in expensive racks.
having a very solid floor is critical for rack performance. i have 6 inches of concrete. the rack cannot fix floor problems.
good luck.