This is one of the biggest myths we’ve seen. I could also easily spend the most time explaining how wrong this idea is. I mean, people have made large wiring brands based entirely around this myth. So what exactly is the claim? Some people believe that pots that are rated within -/+10% sound so much better than the market standard of -/+20%. So why is that not true? As with a lot of these myths, people confuse active and passive circuits. When you add voltage to a certain circuits it amplifies everything. So, in select active circuits you want a tighter tolerance. In Passive circuits its super low voltage. Your Instruments wiring for an example has less than 1volt. So, your market standard for 20% works just fine in that application.