Modifying powercords

[E-Stat]

...does the amp(or other device) inject anything into the grid?

Of course. RFI generated by many household electronic devices (primarily digital) can be "injected" into the house mains. I'm not concerned with cleaning up what gets to my house as much as what's in my house.

I'd take a guess you might not subscribe to the practice of choosing loudspeakers first and everything else afterwards...another error IMO...

You are mistaken as to my priorities.

Here's one
Here's another

...not RFI/EMI issues with after-market powercords...in fact, doing a Google with the RFI-suffix shows only those safety standards as applied to the manufacture of lower voltage(-80vdc)switching supplies and nothing to do with their culpability in the whole RFI matter(although the standards-adherent manufacturers do claim low RFI/EMI levels, but that is a separate issue

Mea culpa. Try IEC801-4. Here's but one European manufactured cord specifically designed for this purpose:

Eupen GNLM

......and this cord clears up digital hash how?...)

Read the provided link. There are two separate strategies.

rw