Ok, this is my third go at writing this post...the last two attempts were wiped by pressing the wrong key on my new laptop! So i'll try not to jinx myself this time.
My first rack was a Standesign rack from the UK which used a tubular steel frame draining down to spikes/cups and wood shelves. It was a sold rack, looked the goods, but had fixed shelves which are a mixed blessing.
My current racks are Taoc ASR series. The Taoc rack uses a die-cast aluminium frame, adjustable composite wood shelves which sit on small adjustable spikes, cast iron inserts, as well as some acoustic cloth inserts to further dampen vibration. The idea is for the tubular alu frame to drain energy to the cast iron spikes/cups.
I use heavier Taoc SCB RS-50G boards in lieu of the standard shelves for my cdp & amp. The mass-loading principle works well in these applications; kind of like science meets brute force. I also use Finite Elemente Cerabase Classic feet in lieu of the factory feet. The Cerabase feet not only look better, but use ball bearing technology to convert vibration to heat.
So in summary, yes a steel or alu frame & wood shelves can be effective. Just pay attention to how the rack drains energy, and ensure it is sold and passes the 'knock test'. If you hear a bit of ringing in the steel frame. there is a number of ways you can tackle that; for example by filling the tubes with sand or ball bearings. Or you could apply sections of viscoelastic material to the inside of the tubes. Isolation feet also help.
