I need help. I'm new to audio gear and don't know anything about amps or DACs besides that they make sound quality better (and that the Astro's mixamp is bad) What amp/DAC (or mix) should I get that is very inexpensive but will give me great sound on Xbox One. I think its 7.1 surround that everyone says is the best? Thanks!

The Astro MixAmp is not bad. Been using them for years. The 1st generation and now the MixAmp Pro. I wouldn't try anything else.

Actually you don't need a DAC since your DSP device is handling that stage.  In a different thread you said you were using the 598's which probably don't need an amp either. If I were you I would get a mixamp since it's pretty much your best option.
 
If your going to get an amp you will need some RCA cables with a 3.5mm stereo male to dual RCA female adapter OR cable. I would get a 25ft cable if you don't have one. http://www.monoprice.com/product?p_id=5601
 
Oh and if you do get a mixamp, make sure to update the firmware.
 
*EDIT looks like they astro came out with a new mixamp.  The pro TR. Also, it looks like mixamp is having a black friday sale today too.  Anyway good luck
 
Also refer to this, its a great guide
http://www.head-fi.org/t/534479/mad-lust-envys-headphone-gaming-guide-5-31-2015-beyer-cop-and-shure-1540-added