Entreq ground conditioners - what's the theory?

not sure, but i'll say that when compared to floating the ground, my rig sounded better w/ TG Audio's AC conditioning box, which only conditions the ground using a specific combination of multiple bybees. hearing is believing. ground is a huge problem.

Ivan, very interesting reply...thanks for taking the time to write that...I'm in Austin, TX...very dry and only about a foot of soil (well sandy and some gravel) before I just hit rock. When it rains...I can definitely hear a improvement in sound quality...

I've been using Entreq for a couple of months now, put me down as a total convert. I'm not a tecchie, so my explanation may be off. Don't shoot me.
From what I gather, components are producing copious amounts of RF/EMI. The earth of each component is expected to deal with this, but if the earth to the whole system is not substantial enough or components are not sufficiently grounded to drain to earth, this deleterious energy will remain in the system and be heard as a colouration.
From what I gather, the Entreq Silver Tellus/Apollo i/cs provide an unadulterated and unimpeded conduit for theis RF/EMI to drain totally away from the component/system and be disposed of away from the system.
Discharging these unwanted energies away results in a stabilising of the soundstage, and removing major veils that had been obscuring true transparency.

Spirit...I wonder how much my Shunyata Triton and Typhon are already contributing here? Maybe I won't experience as much benefit? Not sure if any Shunyata users have tried these grounding boxes...

J, I think you're comparing apples with oranges here. The Shunyata stuff is more down the line of conditioning/filtering ie the system is fed from the Shunyata boxes, whereas the Entreq grounding works in parallel with the system, ie it's not in the signal path, and works alongside, in my case, 4kVA balanced power.
For my part, after the dramatic improvements wrought eliminating my Burmester conditioner and installing balanced/grounding solutions, I'll never go down the conditioning/filtering route again.