Rega Brio weird sound

Bought an new Brio couple of days ago. Im impressed with its drive and good bass beeing such an small and cheap amp. But in upper frequency there is some issues. There is a precence on some cymbals hihats guitars and s in some voices. And it have this annoing hiss. But this "loudness" upper midrange.. is that a Rega/Brio sound signature or will that go away with some more hours on the amp?