Why does my system now have shrill top end.

@uberwaltz  pardon me for saying so but now you’re the one doing it. Walk a mile in my shoes. 👣

Regarding the exchange Jim (Jea48) and I had a few posts back about the "Ortofon Black" cartridge listed in the OP, and the possibility of trying the phono stage connected directly to the power amp:

In addition to the high output 2M Black moving magnet cartridge, which as I indicated would be unsuitable for use with the non-adjustable loading of the Linto phono stage, Ortofon has two low output moving coil models having the word "Black" in their name. Those are the Cadenza Black and the Quintet Black (or Quintet Black S). Both have rated outputs under the standard test conditions of about 0.3 mv.

I assume the OP’s cartridge is one of those two models, and if so I assume he is using the high gain (64 db) setting of the phono stage. 64 db would boost 0.3 mv to about 0.48 volts, which is about 2/3 of the voltage that would drive the amp to full power. So while performing an experiment with the preamp removed from the signal path is probably within reason, especially if a recording known to have low volume is used, and if care is taken to avoid a large transient when the stylus makes contact with the record, personally I would still feel somewhat uncomfortable about doing that.

Reducing the gain of this phono stage to its low gain (54 db) setting, btw, apparently involves cutting a wire internally, so that wouldn’t seem to be a good way of performing the experiment.

Regards,
-- Al

SPEAKERS ! After trying another amp and/or cables I'd try another set of speakers that a friend can bring over. The tweets may've gotten damaged somehow - if that's the case there's nothing you can do to get sweet music back. Find out.

like @jea48  I am waiting to hear if taking the P5 out of the system helped, although his description of the problem didn't seem like noise to me.
Haven't heard from the OP in 5 days....

OP last commented saying he was going to swap the amp this weekend and if not that then look at ac.
This weekend could well be late tonight, we do not know his work schedule.
However if not the amp, I certainly hope he does not jump straight to ac possibilities without at least swapping speaker cables no matter how unlikely that scenario may be. Its cheap, quick and easy.
I am thinking the amp swap will reveal plenty but we just have to wait for now.

Thank you
Kevin

Thanks for all the great suggestions. I turned off all lights in the house and it made no change. For the HOI I changed the power cord from a PS Audio AC5 to the stock cord that came with the amp and although it had no effect on the upper registers it seemed to focus the sound stage more. I guess this is left for another discussion.

I wanted to switch amps but the 5 channel unit I use for the surround sound room is much too heavy for me to easily move. Hopefully I can get a friend to help me and will report back afterwards. I too think it must be the amp but this test will tell for sure.

I too think it must be the amp but this test will tell for sure.

Hopefully Kosst will take my response to this in the constructive spirit in which it is offered: If the problem goes away when the amp is changed, while it would substantially increase the likelihood that the Pass amp is the culprit, it would not by any means be a conclusive indication. It could simply be that the other amp is less sensitive to the effects of a speaker cable having very high capacitance.

Also, can you answer a couple of questions I had raised earlier:

1)What is the full model name of the Ortofon Black cartridge?

2)Do the OCOS cables have a "red" termination network, a "black" termination network, or neither.

Good luck. Regards,
-- Al

About a year ago I was experiencing system symptoms virtually identical to those the OP has described. At some point after much thought, frustration and experimentation, I replaced my speaker cables and the harshness disappeared. 

30 feet of Monster Cable or 12 gauge TW cable from the hardware store will be an easy and inexpensive experiment. Hope this helps.

I'm sure someone has already discussed this possibility, but on two different occasions when your problem arose in my system it was as big a mystery to me as it is to you. I was able to eliminate the problem by addressing the dressing issue and insuring that IC's and PC's were not running parallel nor were they passing close to transformers. Since I did a tear down and reassembly I'm not sure where the villainous wire(s) were but the problem did arise after I had been fiddling in the back of the equipment reconnecting/relocating equipment. FWIW.  

Latest update. Changing the amp made no difference. So all I have left is the speaker wire, the power, the room or my ears. Since the speaker wire shouldn't change nor should the room I am wondering if it is my ears. Next step is to visit a local audio store (if I can find one). Then talking to my electrician about a separate power line,. Will keep you posted.

+1 Jim (Jea48). Although it may seem improbable, I would not by any means rule out the possibility that BOTH amps have succumbed to the very high capacitance of the speaker cables.

Also, I would add the following to the quotes you provided, this one coming from a respected designer of highly regarded audio electronics and speakers:

Pbnaudio 12-1-2017
My gut reaction to this is the very long, highly capacitive speaker wires are at least contributing to this. As someone stated above - try lamp cord.

Best regards,
-- Al

Changing the amp made no difference.

How about swap the preamp?
 

At the risk of repeating myself, this appears to be very much a circuit focused group. It seems my earlier post intimating the problem of the “shrill top end” could be *something else entirely,” something out of the blue, was taken down hard. You know, the suggestion that the culprit could be unrelated to the audio system entirely, I.e., not (rpt not) the amplifier, preamplifier, cables, power cord, room acoustics, or even the house AC. It doesn’t have to be the amp or the preamp. And I am not referring to any of the issues in Vogue such as fuses, wire directionality, polarity, out of phase conditions, things of that nature. But something a little bit scarier. I’ll be watching with some interest to see how this thread plays out. 😀

I am still surprised the OP has not at least tried swapping speaker cables with how cheap, quick and easy it would be to do.......

I added two lights with in-line dimmers to a distant 20 amp outlet that also powers my system. With the lamp dimmers on, it significantly raised a multi-amplifiers operating temperature and added a soft grain in the separately powered mids and tweeters. It disappeared when I turned off the dimmers or unplugged the lights.   

Here is the latest update. I ordered treatment for the side walls and will report back. But wanting to make sure it was not my hearing I visited a nearby audio dealer (Audio Connection) with the same music in hand that sounds so shrill at home. And guess what, it sounds fine in their system. By the way, I listed to the Proac 48r, which I did not like, and the Vandersteen Quatro CT, which I liked so much I may buy them if I can sell my current speakers.

@proacman ,
 Did Johnny have any idea of what may be the problem? He sure knows his stuff.
And, I hope you come over to the V side.
BTW- why are you Proacman if you own Von Schweikert?
Bob

I owned the Response 2 and 2.5 for many years. That is where the name comes from. And is sure is easier to spell than VonSchweikertman.

Heehee...

As an overdue update, I was able to slightly mitigate the harshness by replacing the stock power cord that came with my PS Audio P5 with a PS Audio AC12.