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
There are frequency sweep apps available that may be helpful. Run the sweep via your phone, or computer, connected to your system. You will be able to hear the sweep frequency as it progresses from 20 db up to 20K db. Unfortunately, your hearing may drop off above 10K. If so, you might need a db meter to test for high frequencies. Or use a younger kid who still has good hearing.....
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erik_squires,

I wonder if current batch of Yamaha integrateds (501, 701) has something similar to what you are describing Denon as. A friend of mine has one and it does exactly that, it gets quieter when you engage "loudness" which is actually not a usual old-fashioned button, but a knob with a certain range. It has not worked really well for me so far, to say the least, but I could not believe some fine engineers would put it there if it did not work at all. Next time, I will try making it louder and then using loudness the way you mentioned although, I admit, it seems a bit counterintuitive to me. We will see, I mean...hear.