This mean "use a better source" CMIIW
The Dark Star is more than powerful enough, but your source could be improved by using a decent dac for the conversion. This will give you much better sound quality than using your media player direct to the amp. There are plenty of options out there for great sounding dacs that don't cost the earth. You could look at Odac, Modi, Vdac, Maverick D1 all these will significantly improve the sound and will help with bass etc. You will need to use an iphone/ipod doc to connect to them though.
Naim makes a bunch of DAC's so you'll have to be more specific. They're fairly well known, but their price/performance is lacking unless you get one of their all in wonder units. They're more of a 2ch company than value focused for headphones.
not that good in making a comparison. I just notice the HD800 excels more in soundstage (waay wider) while the LCD-2 has more bass kick for rock music and electronic music. I do like the overall comfort of the HD800 more though. LCD-2s do clamp my ears quite a bit :D. Sound wise, I guess I'll prefer these for electronic music while the HD800 will stay my fav headphone for classical and jazz.