Audio Rack Selection

Bh, the rack is not as important as the floor it is on. The only sensitive item is the turntable. Regardless of what the mythology says the other components could care less what they are in or on.
To test your floor put an end table or small cabinet where you plan to put your rack. Place a 1/2 filled large glass of water on the table and walk around watching the water. You can also try jumping up and down to see what happens. If the water starts wiggling you have a problem. The solutions would be a wall shelf for the turntable or a well tunes suspended turntable like an SME, SOTA or Basis. 
It is better to keep your mono blocks behind the speakers with short speaker wires and long signal wires even if you do not have balanced connections.
After all this buy the rack you can afford that looks the nicest to you.

Mike 

To answer your question, Is there a true need to buy upper tier racks? - Absolutely YES! A well built rack is a foundation of a good system, especially the one that has a TT. I second the recommendation on Core Audio Designs racks. They are built for life and offers superior isolation and dampening like no other racks made from wood.

It appears you need a ‘twin’ rack to accommodate the two mono’s. Give a call to Arnold at Core for one on one consultation.
Good luck!

If you want a recommendation, look at Core Audio Designs: 

http://coreaudiodesigns.com/products/component-racks/

Their products look and perform perfectly. I use one with a TT and McIntosh system. See my previous post on this system.