New expensive power cord for amp and no change in sound?

Somehow I doubt that. If this were true you should mention your experiment, give some details and say you heard no difference. All this other stuff is tribal. You go way past giving your opinion, ridicule others that dont share your opinion so that you are on record so you can find other like minded individuals which gives you comfort.

I am happy to give you a list of all the cables that I have used in the past 5 years. I can give you a list of power conditioners but I dont use these as any gains were offset by diminishments. Please share your experiences. Instead of smug remarks add something to this thread of substance.

Or you can just admit you dont buy into any of this at the theorectical level and be done with it. If you havent tried a bunch of cables no problem but dont get upset if some on this forum think this puts you in no position to comment.

So again why do you care?

westcoast, I think I got you confused with another poster. So my somewhat aggressive stanch may have been directed at another person on this thread. Keep this in mind if you respond. 

I have 2 highly regarded power cords right now. They are both around 10ish years old. New equivalent models would be in the 4K range. Cord one causes a loud hum hooked up to tube integrated. Cord 2 everything is dead quiet. Neither made noise on another amp I had them hooked up to. Strange. 

Most likely some sort of grounding issue. A thing you can try is get a 3 prong to 2 prong cheap adaptor which will remove the grounding pin at the wall outlet to see if this changes things. This is just to identify the problem this is not a permanent solution. FWIW.

@roxy1927,I too have a Pass 250.8 and an ARC REF 6 pre.  Switching from the stock ARC power cord to a Shunyata Alpha v2 yielded a definitely noticeable improvement in the sound.  On the other hand, I first replaced my Pass stock power cord with an Audience Power Chord that I had.  There was a definite improvement in the tightness of the bass, audible but not amazing.  Then I replaced the Audience with another Shunyata Alpha v.2 and really didn’t notice any improvement,  So I think that it depends on whether you are replacing a stock cable and where in the system you place it.