I work with Shop2Market, which means you can send one productfeed to shop2market and via them it goes to amazon, it monitors across all channels and you get a quick idea which products are performing well / and which not and you can even turn of the products in the feed to the retailer. Nowadays I work in gaming industry but my former employer was a clothing retailer. It also works tremendously good with monitoring affiliates.
www.shop2market.com. In the netherlands already many big companies works with their tool.
If you need more information or a direct contact at shop2market just drop my an email.