The switch you have pictured going to your mobo, what's that for? I hope it isn't to turn on the PC, because that one pictured won't do the job hooked straight to your mobo. You could use it on the IGN wire for your PSU. That's what I did in my setup.
Also, you need a negative line for your PSU. And you can use the Amp-on feature of the PSU pictured to turn on your Amp.