How loud is too loud


Hi. Im new to the world of audiophile and am hoping someone can help with a problem only nine months in to spending £3000  on my set up. I've got an audiolab 8200p power amp, audiolab 8300cd and monitor audio silver 8 speakers. After playing some fairly heavy house music at -10db I noticed a distinct lack in sound quality when I played music at a lower volume and now it sounds as if I've lost a whole frequency level. There is not distortion as such, it's just that music sounds quieter and less definition in the top end. I always run my system in before turning up the volume and never push it too hard for too long. Normal listening level is around -30db.
Any suggestions greatly appreciated.
tcapone
I appreciate that my ears may not be as receptive to sound clarity immediately after turning the volume down after listening to loud music but the loss of sound quality is apparent for days after. I have been testing it with electronic dance music, starting off at low volumes building up to -30db, it starts off ok but then it is as if certain frequencies trip the system and I loose depth and loudness in the sound??
Great question;

There are cell apps that record DB for you.

I have a audio group & they all play at different levels.

My ears like softer

When reading & listening -60-65 dB
When really listening - 75-80 dB

One buddy -90-94 dB 

most others -80-85db

yes, I’m geeky
Nothing wrong with a bit of geekiness frozentundra! However, what you suggest is a subjective thing about personal listening levels. This is a definite change from one day to the next in loudness at every level, so when the system is running properly everything is fine, when the fault occurs everything sounds about 10db quieter and almost tinny in the top end. 
I was hoping it was something like damaged tweeters, but I have been unable to replicate the fault at the shop I bought it from when I took it back for them to check out. it seems to be something that occurs after playing 'loud' music?
tcapone,

If the loss of sound quality is still there at loud levels, you blew a driver. if not, you are suddenly self aware of your ear's limitations.

Tuning speakers with a smile like curve helps them sound better at low volumes. Loudness controls in older preamps / receivers was also a great benefit.

Best,

E