Haha so true about the toilet flushing! I've seen a few videos about sump plumbing and with that much water moving so far I can't imagine its perfectly silent. Super impressive if people manage thatHello and welcome to R2R.
You won't find too many people in the hobby that want their aquarium to make any sound. Most people's goal is for their aquarium to be as silent as possible.
My aquarium makes noise from the water going down the overflow and I like the sound, as long as it doesn't sound like a toilet flushing.