As somebody that's been intimately abused by Sarbanes/Oxley part 404 (AKA "the full employment for useless consultants act of 2002") in the IT industry for the last several years, I can offer many stories of wasted time and money over that time. SOX only "solved" the problem of too many American companies being too productive, and it fixed that with plenty of wasted man-hours and consulting fees, and endless paper-acres of documentation of things that nobody will ever read.
But beyond that, the Federal Reserve together with each of it's regional banks is already audited every year by an outside accounting firm (lately: Deloitte Touche) and the opinions and reports, with notes, are posted online for anybody to look at. I've looked at them. I still haven't heard from anybody what some other audit is supposed to reveal that their annual audit doesn't.