Depending on how austere your listening area is, you might be finding that seemingly trivial differences (books piled up on coffee table, doors open or closed) might be affecting the room.

I always wonder about things like humidity & temperature affecting speed of sound and subtly affecting room resonances, but all the charts stubbornly refuse to show significant differences at comfortable-for-human temperatures (60-80C is a different story though).

That said, I do experience the same "sometimes the sound is just better than other times" effect, although I have never controlled choice of recordings enough to be sure it is happening.


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8