Loss of Highs

Here is my problem. A few weeks ago I replaced a tube in my Aesthetix Rhea which seemed to causes some intermittent fluttering in the right channel. Turned out it was the right channel V1 12AX7. Anyways, I replaced both V1’s with Gold pin Electro Harmonix 12AX7’s. While I played some music with the new tubes, I noticed the fluttering was gone, but there was a bit more noise coming from one of the new tubes. I decided to put the old tubes in, and order another set of new tubes. Anyways, after I put the original tubes back, I noticed that my highs seemed to be diminished somewhat. The music sounded a little dull and some of the air seemed to vanish. I can’t figure out whats wrong!

When I play an LP vs. the CD version the same album, the LP still has more fullness to it, but the highs just seem flat compared to the CD version. Symbols with the CD seem to shimmer more and have more air to them than the LP. It use to be the other way around until I swapped the tubes out!

I have a Rega P5 with a Glider SL and have double checked the tracking force, anti-skate, and made sure the table was level! Everything is perfect! All of the tubes are seated correctly and the cartridge loading and gain are where they always have been! I even tried another pair of tubes and nothing changed! I just cant figure out what is wrong! Any ideas?

The original tubes did not sound bad, I just noticed an intermittent fluttering noise coming from the right channel that prompted me to change the tube.

Any ideas of what may be wrong, or recommendations would be appreciated!

Thank you for your help!
Yep, good luck with that noise. It sounds like it might be an older Rhea. I owned one, for a little while.
I'm thinking what Elevick is thinking.
Except for the laughing part. I'd never laugh at a guy who's experiencing diminished highs.
The new tubes that replaced the old did not sound much different than the stock tubes. I only noticed much more tube noise with one of the new tubes, and the fluttering noise ceased. Thats why I put the old tubes back. I noticed the diminished highs after i put the old tubes back.

I have heard the cell phone fluttering before, but that usually only happens if I am very close to my equipment and I am about to receive a phone call or text, then the noise goes away. I have tried a third set of new tubes with the same result.

I guess I will have to send my unit into Aesthetix to be looked at, or re-tubed.

Oh, and I did double check all of the settings in regards to loading, gain, and interconnects. Everything was set correctly. Thanks again for all the suggestions.