Help with hiss

@2psyop Thanks for sharing. I’m really sorry to hear of your experience. Mine has been the complete opposite. I’m sure there’s stories of great successes and not so great in every manufacturer’s history. I’m glad you found your resolve and are back to digging’ the tunes!

@audphile1 👍🏻 I’m with you!

@tempostarship Thank you for that. I had given some thought to doing that, but I wanted to isolate components first. It would be a lot of moving, as there are no other outlets in close proximity. I don’t want to use an extension cord because that could create problems of its own. So, I’d have to move the amps and speakers to another location. That would be the easy part. Putting them back where I had them would be the hard part!

@rockadanny Thanks. I wouldn’t expect it from static gear either, but I’m glad for some confirmation.

There have been some magnificent suggestions here, which is exactly what I was looking for. I had thought this thing to death and I was running myself in circles. I remain open to any ideas or thoughts people may have. I am not quick to fault the amps themselves, primarily because the hiss level, frequency, constant vs. pulsing, silence etc. is identical in both channels. It seems that if it were an issue with one of the amps, some of which were suggested here, I would expect one channel to have an issue but not both. In fact, while troubleshooting, I turned off and unplugged one amp but the other continued to hiss. I turned off and unplugged the other amp and the other one continued to hiss. 
Maybe coincidental, maybe wishful thinking, maybe an Audiogon forum exorcism, but since I got up Sunday morning I have not heard them hiss. I also have not played any music yet. And my neighbor hasn’t been home🤷‍♂️🤔

OK..have some answers here....

first off,  apologies for the delays,  but I also have always been upfront with the timing...we are hammered !!!and no,  of course I'm not sending back units with the exact same problem,  that's bs.  however,  when I change or upgrade amplifiers and put them both,  in my own system and on the bench,  and they a behave perfectly,  then they'll go out.  However,  when you get the same units in your system and then they misbehave then obviously something somewhere makes them go off the rails.....now,  there is a simple way to check what kind of hiss or hum is going on:  if it stays the same volume regardless of volume then it is AC  related (and approaching the proverbial needle in a haystack situation) and not inter-system problematic...also,  if there's something wrong with an amp...or a pre for that matter then the hum would be there constantly...there's no "muscle-memory"  that kicks in,  and thus a dead give-away for some environmental problems...on the  flip side,  yes,  some units,  i.e. power supplies are more susceptible to environs (halogen lamps,  fridges,  outside lights,  anything that neighbors have and do before you in the grid,  etc.)  than others,  and  oxymoronically,  bigger and higher grade power supplies act up easier...that's what I found on our and on other brands gear (on which I worked on for friends) as well.....go figure.

But then again,  there  are devices (humbusters etc.)  that will take care of situational problems....all I can say on my side is that if there is a problem,  stay on my ass...one way or the other I'll make it right............and I do take exception about the "excuses" thing...taking a lot of time, (sometimes my schedule,  other times parts availability, especially the past 2 years)    unfortunately possible,  but I'll never lie to you....at this point of writing,  I have 65 amps here for Kismet upgrades,  and more than half for the hyper power supply upgrades.  In addition to regular orders.....and we hand made over 7500 amps over the last 20 + years.  99 + %  of them without any problems...you never hear about them...and yup,  I mess up from time to time as well...sorry.

Hope that helps,  and just  get back with me,

Klaus

@forestg

OK so it sure sounds like its a power problem coming into your house. Your last post about plugging/unplugging each amp amp in turn and they exhibit the same symptom individually. Next step for me would be to purchase an isolation transformer and locate it in another area. I’m not talking about power conditioner here, but a real medical grade isolation transformer. A little pricey, but it will stop you from pulling your hair out. Good luck.

Regards,

barts

If it can’t be heard while music is playing, then why worry....there is some degree of hiss or noise in ever system. It depends how sensitive you are too it. My tubed phono preamp is noisier than my solid State. However, once the music is playing, I'll take the tubed phono any day...

What power issue would cause an audio component to hiss? We are still talking about hiss are we? Hiss as in ssssssss type sound. Not the hmmmmmmm sound. Correct? 

Amplifier or preamplifier hiss can go unnoticed or may not be as noticeable if you have inefficient speakers. Once you move to a pair of speakers that are above 91 or so db efficiency from an 85db speaker the hiss will be more apparent. 
 

There’s something fishy going on here that sounds like some sort of a user error or a faulty piece of electronic equipment in the signal chain or a pair of new very efficient speakers is revealing this hiss. Very curios now….