An audio rack that really does make a difference.

I'm a proponent of putting the rack at the side of the room and keeping the space between the speakers open. The best results I've gotten are from using long(ish) balanced cables to monoblock amps which sit directly behind (or just to the side of) the speakers on low supports with short speaker cables. 

Just to answer your question, stabilization of the equipment/speakers through vibration control is very important.  I've gone through three setups over 50+ years.  For the past 25 years, I have hollow, heavy gauge welded steel racks filled with 50/50 mix of shot/sand with a mix of granite and high density fiberboard shelving and various Stillpoint devices under almost all equipment.  You will notice the difference with superior shelving and you won't regret it but don't cheap out as you can keep great shelving for many decades.  

Love my Timbernation - beautiful and very solid!

Does anyone own the Dovetail audio rack from Symbol Audio?

"SolidSteel "brand audio racks would be another option.