Off hand it looks like your overspending on several parts which won't net you performance. Though I am more familar with prices and shops in the US/Canada I can't really make a recommendation for australia.
Offhand you should be able to use a cheaper mobo, the gpu would be overpriced if that was the price over here so I would just pick up a 670 with a good heatsink and OC it to where you want. I also wouldn't bother with the platinum rated PSU and just get some type of good 80+ rated PSU as you can free up a lot of money there. You can also get a high end air heatsink for cheaper instead of closed loop water cooling. And probably a cheaper case if you want to. As for controling sound level hopefully the expensive keyboard your buying has a button for that if not you can probably program some buttons to control it. I know I use my multimedia to control the audio level to my Superlux HD-668b/Xonar DG and it only took about a day to get used to doing it that way and I find using knobs more annoying now as I have to reach for it where as the button is only a finger tip away.
That headphone and sound card setup is bad. You can do a LOT better for the price for the headphones, and honestly if you were going to keep using those headphones I pair it up with an Xonar DG or Xonar DGX which has a built in amp which can drive 150ohm headphones and have dolby surround option for normal headphones rather than rely on whatever setup they are using. My honest reccomendation is go over to http://www.head-fi.org/ and ask them for reccomendtions as you get the help from several audiophiles who can help you at any price point, they will set you in the right direction. Just trust me on this your ears will thank you when you experience good audio.