As more a fish phile then audio so far...you guy's left out the idea of an all natural tank using live mud sitting on platic egg crates for the natural way to break down nitrates. And then put any powerheads on a timer or shut them off when your listening.Or any of the Eheim/Fluval type filters are dead quiet. But for me I keep my two hobby's separate. I do believe that the unnatural vibration the music produces is stressful to them.
Clavio
Clavio