You mean the center, right? ;)
Make sure to include the rechargeable battery pack, just for practicality. I didn't and bought my own eneloop rechargeable batteries thinking they would charge through the Rx Unit.... they don't. Now I have to remove my batteries and charge them on their own time. A hassle. <_<
Also, keep in mind the Mixamp 5.8 only has ONE optical input, so if you have more than one system, you'll have to get an optical switcher like I linked, or constantly remove the optical cables when switching.
So for newbies:
1. Mixamp 5.8 ($140)
2. Astro Rechargeable battery pack ($20)
3. Astro 3.5mm to USB cable ($10. Only needed if you plan on voice chatting through PS3)
4. Optical (toslink) switcher ($20 on Amazon. Only if you have multiple game systems like a PS3 and 360. Do NOT get the cheap silver and purple one. TRUST me, it sucks. I'd get the black one.)
4. 2 optical cables (buy them off monoprice or Amazon for dirt cheap. All optical cables have the same exact SQ, so the cheapest without heavy jacks work best). The 5.8 brings a very frail optical cable so use that as the one that goes from the switcher to the Mixamp.
That will be all you need. The Mixamp 5.8 brings all other cables you need.
Oh yes, not sure if I even need to mention this, but older XBox 360s don't have an optical out, so make sure to get the audio dongle that brings an optical out (when you use HDMI).