AMPLIFIER TEST ON SHELF VIBRATIONS recently published the results of the lab evaluation of two Tandem-Audio rack models. As you can read in the whole article:

“During this lab evaluation, we tried to find some data on how the Statement and Ultimate worked, and if they perform the way Tandem says they should, aiming to form an objective basis on which to support some conclusions. Measurements were made with an acceleration meter which was placed at two points, directly on the stand surface and on the top of the chassis of a power amplifier. The amplifier used was our standard reference amp (Parasound HCA3500) at its normal position in our listening room, i.e. where it is always during our listening sessions. This is important in the case where an excitation through the loudspeakers is included during the measurement.
The two stands replaced the one that is usually used for the support of the amplifier (a simple wooden shelf with castor wheels from Exelixis). The whole procedure included both measurements with the amplifier driving the loudspeakers at a normal reference level (73dBSPL/2.8m with a pink noise signal at -20dBFS level) and with the amplifier idling, without any input signal.”

The below Graph is from Statement series evaluation test