Barometric pressure, temperature, moon phase?

Are you using class D? Did you leave them off for a couple of days?

Sure....everything changes everything....a local airport with radar on, power grid, a/c, tv in the next room, etc.

Viridian, now that’s truly sage advice.

erik, no class D, Parasound JC1 monos, and the rig has been running for several hours.  When not active, they’re always in stand by mode.

stringreen, yep, everything is always in the mix.

I’ve noticed this phenomenon from time to time, and tried to think through what variables might be causing it when I notice it.  Still no answer, but it done make me appreciate it more when the whole thing sounds great.  Silver linings...

+1 kosst_amojan! Hearing perception is the most variable factor in the listening experience! 

The sound is influenced by external physical factors such as weather 🌧 barometric pressure and sunspot activity 🌞, radio frequency activity, vibration, etc. that affect the power grid and electronic equipment, cables and house wiring. The brain and perception of sound, on the other hand, are influenced by any number of (mostly undocumented) external factors, many of which are subconsciously received or interacted with. In that respect the brain acts much like a radio transceiver. As the little mice in the movie Babe 🐷 sing, That’s the way things are! 🐭 🐭 🐭

Music, like sex, is best enjoyed when one is in the mood for it!

Let us know how it goes tonight.

Our bodies are a receiver - we have all kinds of circuit noise - blood pressure, hormone levels, state of mind, chemical imbalances, insulin spikes, etc...you get the point.  We are always so quick to attribute an outside issue to change in how we perceive sound/music when it may actually lie from within?  Everything matters ;-)

I just noticed @kosst was looking at this similar to my first reaction.  Sorry if my thoughts were redundant!

Weather can be a big determinant in your mood and therefore, your listening pleasure. WiFi is noxious to some people and to those who can tolerate it, or don't even notice it, it can still be negatively affecting you without you being aware of it. It's all over the place.

Factor in microwave transmissions and how your day was by the time you sat down to listen and it's no wonder why sometimes your system just doesn't cut it. 

All the best,
Nonoise

Caused by sun spots or the lack of sun spots.

Remove your hat.

I agree w/elizabeth could be sinus/middle ear related.  Since I was 30-something I have had allergies year-round where I live (tree and grass pollen) and it definitely affects hearing.  I take Loratadine daily and it seems to help.

Perceptions are NOT reality. They are just perceptions.

Perception IS reality. Our sensory perceptions are precisely how we observe reality. The word perception can sometimes be used as a psychological term, but it’s actually not. It’s the same thing as hearing. There’s no difference.

Be it sight, sound, the smell, the touch.
There's something,
Inside that we need so much,
The sight of a touch, or the scent of a sound,Or the strength of an arquebus deep in the ground.
The wonder of flowers, to be covered, and then to burst up,
through tarmack, to the sun again,
Or to fly to the sun without burning a wing,To lie in the meadow and hear the grass sing,
To have all these things in our memories hoard,
And to use them,
To help us,To find...

@dprincipato
You may find http://ielogical.com/Audio/WinterBlues.php interesting and specifically http://ielogical.com/Audio/WinterBlues.php#TheFly for the effect of temperature on speaker XOver

You did not mention the source. LP playback systems are subject to all manner of temperature related foibles: bearing tolerance, lubrication viscosity, cantilever suspension compliance, vinyl plasticity.

Do you note levels at which you play a particular piece?
How repeatable is your level control?

When mixing, we calibrated the playback level to the speakers to ±0.1db. The room was temperature controlled to ±1.0°F. When we were satisfied, we always checked the next day on cold monitors. Mixes made in the heat of summer sounded different even though the room temperature was nearly identical as rooms were not humidity controlled. Line voltage and dirt varies considerably in Los Angeles, so we recorded and mixed late a night when the vagaries were minimized.

Perceptions are NOT reality. They are just perceptions.

Science provides us with zero evidence the entire known universe is anything other than a lot of particles and charges just zinging around all over the place. There is in this world no light, no color, no sound, no heat- and certainly not any hard or soft, good or bad, pleasing or aggravating or anything else. There is no music in this world.

Them’s the facts.

Until, that is, any of these particles or charges interacts with our senses. Then and only then do the patterns of greater and lesser density atmospheric molecules become sound.


In other words, just to hammer the point home, it is not merely the case that there is no other reality than our perceptions. The fact of the matter is our perceptions create reality.

Learn something new every day, pwkmaven2.

Case in point.

the stereo sounds ever so slightly, not quite there.  It did the other day, but tonight, it’s missing some tiny bit of something.  Has this ever been experienced by any of you out there?  One day magnificent, another day, just ever so slightly not quite as good.

I used to think this was nonsense. Sounds better after warm up? Sounds better late at night? On and on. All pure, unadulterated BS. No way.

But I really, really care how my music sounds. So if there's any chance at all.... 

First I left everything turned on all the time. Did this for quite a while. Never noticed anything. Then after everything being on all the time for weeks for some reason everything got turned off. Oh well, whatever, like it matters. Only when I did turn it back on, wtf? What is that awful grainy etched crap that used to be music? Oh. So that's how I learned to hear the difference between cold and burned-in warmed up sound.

If you're noticing these fine differences I would suggest you try a few things like this. A lot of these things are subtle and change very gradually over time. The slow gradual improvement in performance as my gear was run 24/7 was hard to notice. Until I turned it off and then listened to it cold. Then it was obvious.

Other things that are now obvious-
Unplug something or even just wiggle the wires around its gonna sound bad for a while
If you just play music day after day the sound slowly degrades, but slow and gradual enough you will never notice, until you run a demagnetizing track and then Holy Smokes massive grain and glare disappears. 
Pretty much everything will warm up and sound better just by being turned on. Its not necessary to play music. Except for the cartridge. The first side never sounds all that good.

There's a lot more. Pretty much everything everyone above has said does indeed have a very real effect on the sound. In my system it all adds up to where it just keeps sounding better and better and unbelievably better until dang its late got to get to bed. Next day, crap. Relative to what it was.

The trend is not (rpt not) your friend as warmer temps produce more rain, more low pressure systems, more wind, more wave action on the shore, more flooding - none of which are good for the sound. Not to mention your chances of getting eaten by a shark go way up. Beach forecast - partly sunny, scattered sharks in the afternoon. 🦈

Thank you all for your input, the source was red book cd.  No cables or connections recently disturbed.  
The effect was slight, seemed normal the next day, I’m gonna chalk it up to ear wax, and Russian election interference effects, both electronic and psychological.  
Sounds good this morning, and I’m just going to enjoy!

Thanks to all!

And so after all that it turns out this was just another case of too much CNN.

Trying to deflect something that happened recently in an offhanded way?

I only worry about phase of the moon when it is full........

Seriously though.

I would have to agree with Kosst entirely.

Example.

Last week was working in a factory in Texas, hotter than hot, bad job all round, behind schedule ( contractors not me). Owner none too happy, so just pretty miserable experience.
Got home late Friday, finally sat down 11pm and put a record on, switched off by track two as sounded awful.

Fast forward to this afternoon, all the honeydew list knocked out, just come out of the pool and feeling pretty good.

Put the very same record on with no changes bar my mood and it sounds really sweet......

Sort of makes ya wonder just how much of this Audiophool crap is in the mind.....

Perceptions are NOT reality. They are just perceptions.

What we perceive is effected buy our self, body, and pre-existing beliefs / needs / fears / mood / etc. It's almost impossible to separate what we believe, what we need to be, and what IS. This is why it is such a vigorous point of discussion (taking the high road here).

Question: How do you determine what is right?

Answer: Measure ALL and see what is truth w/o your own bias.

Question: What happens when the measures don't reveal what you want (or think you hear)?

Answer: Research better measures OR accept that what you perceive is just that (for now) and do what you enjoy. We cannot agree as we are all different individuals with different strengths, weaknesses, AND therefore perceptions.

Question: Why do some NEED to be right?

Answer: Ask my ex.

Our audio stuff is very personal. A green shirt is never ever correct - but if you like green - wear it.

Brown shirts however should be avoided.

Empirical observations - i.e, perceptions - are a cornerstone of the scientific method. Get with the program. Deprogrammers are standing by. We perceive with our senses. I perceive the web you weave.

brown shirt

Einstein was a bit of an old fogey. He would have made a very bad audiophile. You have to learn to trust your senses! There are a great number of audiophiles by my reckoning who don’t really know what they are hearing or where their sound stacks up in the overall scale of things. Everything is relative.

Ironically, perhaps, Einstein was wrong about black holes and quantum mechanics, believing they were not real, two things he would have been unable to observe 👀 with his senses.

Ouch!
Very ouch!!

kosst_amojan

If you ever worked at NASA, you plunged toilets there because nobody with any education would say such stupid things.

Ad hominem attacks - aka "insults" - are one of the most basic of the logical fallacies. It makes your argument self-defeating and undermines whatever credibility you might have earned. And, often, it gets your post deleted. So what's the point?

I was an analyst for the ISEE (International Sun-Earth Explorer) -C scientific satellite 🛰 that was station kept at the Lagrange point a million miles away from Earth where it collected high energy physics data. At the end of its mission ISEE-C was directed into a slingshot maneuver around the sun, to gather momentum, a maneuver duplicated in the movie The Martian. From there ISEE-C was directed to rendezvous with a comet ☄️- Comet Giacobini–Zinner - that happened to be in the neighborhood. That maneuver was also duplicated in The Martian when the crew rescued Matt Damon. I also was a senior mathematician at NASA analyzing radar tracking data. I also won the paper airplane distance contest at Lockheed Martin.

Your system has what I call a cold. Lol. High humidity, static electricity in your cables or dirty power. It could be your mood. Music always sounds better when your happy.

Tyler the Creator Merch piques my attention. Please tell me this item is suitable for the winter. I'd want to purchase something for my children.