Well I can hear a repetitive rattling sound on the low bass notes, but it is rattling very fast and evenly. So I call that tinny.

A pure treble note like from a computer wave form does not rattle like that, to my ears.

A normal piano is supposed to have impure frequencies, it's part of the timbre and what gives it warmth.

Like a chocolate or winey kind of muddy. Artistically I much prefer that.