Tax avoidance -- that is, legally reducing your tax bill -- is as American as apple pie. But the line between tax avoidance and tax evasion is often a grey one. On today’s show, a collaboration with Tax Notes , we listen in on the secret tapes that show how the wealthiest Americans avoid taxes. We trace the lifecycle of a tax loophole: how it was born (in Malta), how it grew, how the Feds…