I don't know how much e09k outputs at 50 ohms, but magni will be better since it outputs a full watt.
The e09k will be decent probably... but for just a few extra bucks, magni will be a decent improvement.
But if you're only going to be using the headphones for movies and games, there's honestly no need to spend $1000.
I play games too and watch shows all the time. With the LCD-2's I don't really hear a difference with shows or games.
I am amazed by it every time I listen to music, but I hardly notice the difference with games.
IMO it's not worth if you are not going to use it primarily for music.
Maybe I'm just too focused on the picture to analyze the sound, but if I don't pay attention to it, nothing really jumps out at me regarding the difference between using my LCD's or AKG's.
On the other hand, the AKG's absolutely suck in comparison for music compared to the LCD.
If you have the money, go for it, don't let me stop you.
But I think for movies and games, HD598 are as high as you need to go.
If something about them is bothering you... then maybe look at some other brands.
A relatively cheap recommendation is the HE-400. You can keep the amp dac you have right now with it.
Amazing life-like quality and separation.
I think for $400 that'll be a good change/upgrade from 598's for you.
... kinda regret selling my HE-400's now =/ haha.