New rack or power conditioner

I was going to recommend swapping out the MDF for slate pieces until I read your comment saying you're tired of the look. My rack is similar but with slate shelves. very heavy and solid feel. They pass the knuckle test with no ringing, just a dull thud that can be painful.
Mine is nearly ten years old and I am tired of looking at it but don't want to pay for better performance.

neither is that important as is room treatment...Can the power condition. Most if not all make no change at all. The room and only the room will make all the difference in a better sound system...the best of luck...

what is your budget?

I have done both and both were big improvements. It is kind of the “weakest link in the chain thing”. I would do one and put the other on the to-do-list for a later fun project.

Around $2500 is the budget. I think for now the room treatments are fine.
The Quadraspire rack I saw on another site. I am not that fond of the bamboo shelves. It is not a hardwood, and I would think that the shelves will flex over time and humidity.