Do you ever doubt you ears ?

how about : "how confident are you in the acuity of your hearing? ".

sense perception is imperfect so whether one doubts one ears are not it is possible to be certain of one's perception.

Never.

They are what I use to listen to the music with.

Reading the sheet music or looking at component specs never gives me the same enjoyment as listening with my ears.

Perception by its very nature defies certainty...that's what makes it interesting, and what makes music musical.

Do I trust my ears? I do and I don't. The problem to me, is what others have alluded to. I can always hear a difference in any change to my system. but is it better, or just different?

I believe our brains are hard wired to seek change, differnce, in what we see, hear etc. This means an inate prejudice to what is new. To me it nearly always sounds better. The only answer, as URu975 says, is does the change meet the test of time. Does a new component make you want to listen more over time? Are you listening to different music? In other words, has the change favoured a particular genre of music? For example, I have just added a SET amp to a hybrid integrated, both are wonderful, but I find myself picking out small scale Jazz or singer songwriter albuns, rather than classical symphonies.

>>Do you ever doubt your ears?<<

Never.