I just purchased a used Astro Mixamp and a pair of Turtle Beach HPX headset. I also went out and bought a fiber optical cable and tried hooking it up last night. I did not have any luck though. Can anyone please help me so I can try this setup out. Here is what I did to try to connect them to my PS3... I connected the optical cable to the back of the PS3 and to the astro mixamp. I connected the usb to mini usb to ps3 and then to the mixamp, respectively. I then plugged the hpx headset to the cable that connects the headset to the mixamp and plugged it into the mixamp. I then went to the ps3 XMB and selected Settings->Accessory settings-> Audio Device and in this menu it would NOT let me choose "Generic USB Audio Device" or the "C-Media USB Audio Device". All three menu items were grayed out and would not let me change them. One was set to default and the other was not the headset. I beleive it was the tv audio. I then got frustrated and tried reconnecting everything and made sure it was all connected properly and securely. I also went into Settings-> Sound Settings-> Audio Output settings and made sure I specified Optical Digital output. I then selected "Dolby Digital 5.1 Ch" for the output format. Still NOTHING! Not sure what I am doing wrong and I was hoping someone could point me in the right direction. Does this have anything to do with me needing a Astro PS3 Mic Adapter? I could get NO sound out of the headphones and I could not hear my voice. Any help would greatly be appreciated.