Hey Chuckle, if this is a true portable rig, any amp over $250 is gonna be overkill. If this is your home rig, then it's a different story. Get the M100's, spend some time with them and the E11, then decide what's missing if anything and go from there.
Notice how I stated, "what's missing". Normal hearing will usually find your setup to be quite sufficient. However, if you must spend money for your music to sound good (like everyone else around here), then go for it. Make some amp manufacturer that much more money. Seriously though, Leckerton is fine, if you must spend money. Do yourself a favor though. Keep the E11 and compare the Leckerton or iDevice to the E11 and see what the real difference sounds like. Let me know what you find out.
PS. Remember to enjoy the music. And, if you like bass, which I assume you do looking at your choice of "bassphone", I'd ditch the iPod for a Cowon. Nice warm sound without EQ. With EQ, you're gonna be in heaven.