I will try sorbothane feet on the pre, DAC and amps next. Any suggestions greatly appreciated.
Low cost and efficient.... try a sandwich of quartz feet , very small one, on top granite plate, sorbothane duro 70 on top, another granite plateon top, on top a cork plate, on top a bamboo plate, sorbothane duro 70 under the speakers.... If you can load the speakers with some load on top it will be better... ( 60 pounds for me on each speakers)
All in all that cost me under 100 dollars....My speakers are on the same desk than my computer and dac and amplifier.... They are relatively big Mission Cyrus 781 speakers with great bass.... at any volume with one finger on my desk I sens no vibrations at all.... There is some but under my finger capacity to sense them.... Resonance vibration controls is 20% of S. Q. ….30% is electrical grid controls and filtering...%0 % is acoustical treatment active and passive...
There is another possibilities a quartz sand wooden box under the speakers will do....