My setup consists of Yamaha RXV540, Pioneer DV366 and Lithos Satellites, a passive and an active Sub. I experience the following while playing audio cds. The sound quality is good at moderate amplification. I increase the volume (-35DB on my amp, do not know what is it equivalent to on other amps). The sound quality is alright except that some notes in music become ear piercing. Espeically selective notes played on Piano, Synth and some vocal notes.
What is causing this effect? Is it the way music is or is the system not producing the sound correctly? Or could it be the room as there is no acoustic treatment?

Thanks