How important is the rack you use for your components

I have all home made bases or tables for my components. All are made of MDF. I do have four conical shaped metal devices I found made a huge improvement on my CD player. Sometimes I play cd's, which are very bass heavy and I was getting enough vibration to upset the playing of the cd. I tried the cones and they made playback possible, with no skipping. I had tried rubber feet, as well as Vibrapods to no avail. My TT platform kinda floats. I have it on a second story floor with springs and cables pulling it out from the wall. I tried a wall platform, but still had acoustic vibration. The platform doesn't touch the wall and is suspended, in a manner of speaking, from the wall and floor. I've enjoyed great success with this design. I know there are very expensive platforms made for extremely high tech equipment, but at $5K a piece, I elected to build my own. 

prof is completely correct

Sure, "let your ears be your guide."  But ONLY your ears, not your expectation bias

so, do blind testing

As with cables, the more refined your gear, the more difference a quality audio rack makes. That is just my personal experience and therefor it is just one anecdotal data point that is infinitesimally significant. I went from an el-cheapo threaded rebar and mdf shelf to a Symposium Osiris Ultimate and there were huge benefits. The most obvious-a hum problem I had due to my Manley Steelhead picking up MFI/RFI vanished. Peter of Symposium touts the Osiris as having a Faraday Cage design implemented into the design principal. I was skeptical and bought it for the resonance control. Now, well hearing-or not hearing-is believing.