Using 2 amps at once

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.)