I think you can get a powerful enough amp for IEMs inside a DAP. I also believe the sound can be refined to get to the level of a high quality external amp (again, for IEMs) from a good DAP. This also eliminates the need for a cable and the plugs/jacks to connect a DAP to an external amp, which is an advantage. Whenever you can shorten the signal paths, eliminate connectors and plugs, etc. - this is a good thing IMHO.
For the AKs this is the defining reason as to why I use this DAP, or would any other make DAP for that matter. I went from a brick to the AK and compromised not on the SQ but the UI. Say what you will about iTunes but the iPod user interface is the most stable and easiest to use ever.
I'm so glad that Vinnie has made this statement about amps inside a DAP and IEMs. Thank you.