The "signal ground" tactic to a DIY "signal grounding box" worked very well on my system. The ground leads buried in the grounding box material (fine quartz sand mixed with fine graphite powder) are soldered to RCA connectors which are then plugged into unused RCA connections on the back of the CD transport and the DAC. Each component had its own dedicated grounding box.As per a suggestion I heard from Caelin Gabriel of Shunyata in an old interview I grounded only two source components. This instantly sucked noise out of my system - not subtle. The system was already on a dedicated line, so there was still enough noise left in the system that grounding boxes made an audible difference.
Affordable Grounding
My Frankenstereo has assorted grounding elements behind the rack. The head end of the streaming chain is in another room. At the wall outlet, there’s Nordost QBase 4 Mk II – with a ground lug.
I tried this inexpensive grounding tweak clipped on to the lug. Subtle – but it works. More transparency. Probably similar results with the Puritan Ground Master – and other brands. Worth a try! Certainly more affordable than an Entreq. I purchased the cheapest one with the copper wire/paper cylinder. (Not a fan of silver-plated wire.)
YMMV