Max,
I bought (the correct type/number of) Panda Feet for the DAC and CDP, but can't say that I noticed any difference. OTOH I'm in temporary digs and will need room treatment, etc. first when the system finally gets into its permanent home. Currently the 100 pound speakers sit on hardwood floors that we're trying to sell so the plastic numbs are fine, but the permanent place will be carpet/pad on concrete, so I'll do the spikes then.
I'm also not into audio racks. I've looked hard at them and in a cost is no object/ultimate system world I'd do it. In fact I'll be using a small $30 Ikea nightstand for a rack in my $3000 system. With a background in structural engineering and having dabbled in structural dynamics I just can't accept the value of special racks or feet at "ordinary" spls given the limited energy levels. Vinyl playback and spongy floors are a different matter, but I'll be using concrete slab on grade and PC.
And while I've easily heard the difference between $1000 speaker cables, I'm currently using single pair of cryo'd single strand plenum rated CAT5 that I got for $20 on a group buy a year ago. It gives up some bass, but the rest of it's performance more than makes up.