Grounding Question

My friend had used a cheater plug for a decade on his RAM-9 amp.  I told him to remove it and also replaced a very old cheap power outlet (I gave him a Black Synergistic Research plug).  The difference in his system is phenomenal.  Never use a cheater plug on tube amps or pre-amps.  Probably never use them because they usually are made of inferior/garbage quality contacts, case, etc.  

If it came with a two prong power cord get an AFCI/GFCI combo receptacle. Sure are a lot of clowns on this site!

I do admit that I did take my schooling a long time ago but US Electrical Code has changed very little

Are you kidding??? 🤣

Well, it changes less often than the weather, lol.

As mentioned, a star ground for all components is recommended. In reality, trial and error may reveal less groud loop hum with some components not connected.  It becomes more magic than science, the scientific reason being discovered after the fact.  It is worth going through a "finished" system with a scope on the output to get a few dB more S/N.