I haven't bought a SPL meter yet but have listened to some music with the EQ On and OFF and have to say that for now, I prefer with the EQ ON. This might be due to the fact that my room is very bad for acoustic. 20 x 11 ft, hardwood floors (I still need to buy a rug) and plain walls with no curtains. So even if in general it's not a good idea to modify the speakers performance to compensate for a bad room, in my case, it seems to help... Or I am might already be used to the sound, I don't know...
Will the auto EQ effect sound quality? Yes it will. Ultimately it is up to the end user and what he/she prefers. There is no right or wrong answer despite strong opinions on both sides of the argument. If you like what Audyssey did leave it on.
