[1212magicman]

I got the Ultrasone Dj1 headphones (HFI-580) and un-amped they have okay bass, but they truly have so much impact when amped.
I am a basshead when it comes to watching movies and playing games.

Therefor I bought a Fiio E5, which was lousy... it had buzz lowered treble, but none the less worked a little.
Then I bought a Turtle Beach DSS. LOVED IT. Quality was excellent, digital audio was so nice. Bass was increased.
I experimented and double amped, I used a Fiio E5 AND the Turtle Beach DSS amp. Bass was Perfect.
However the E5 truly brought down the quality.

I'm wondering if it would be a good idea to sell the E5 and buy the E11. Its portable as well, by far more quality, and adds more gain and bass.
Are there any alternatives and is double amping worth the money?

(I'm using this for the Xbox 360 which does not have a Bass Boost feature. But I also use it on my desktop which DOES have bass boost.)

 

[tme110]

Im not sure how amping an amped signal can ever have good results - amps are designed to accept a line-level input and something else would over drive them and clip them which would sound bad and could cause HP damage. 
 
I'm not familiar with those hp's or their amping requirements. The e11 is a nice amp and more powerful than the e5 - I would guess it would have enough power for your phones but don't quote me.  But if they don't work, just send them back. Significantly more power can be had with the e9 or nfb-12 and you wouldn't need to double amp them for any headphone.  The nfb-12 also comes with a DAC so depending on what other gear you have that could mean a significant increase in sound quality.