I wanted to clarify (as an author who works with amazon) Amazon does not require DRM.
Want to publish your book DRM free with amazon? That is a CHECKBOX on their interface.
All of my novels are published DRM free in the kindle store. I insisted on it because DRM is annoying to ME as a paying customer, because I like to decide which readers I read my books on personally, and I would like to afford my customers and fans (even the ones that pirate) the same courtesy.
The first time a fan comes up to you sheepishly and says "I saw your book on TPB and started reading it, and well... can you sign this hardback for me, I bought all your other books too." You really get it.
I push (and sometimes pay personally) to have my books in libraries, I made sure they are available for free in the kindle lending library, I make sure they are DRM free, I have to respect my customers, or they will never respect me.