QUOTE(Smok3y666 @ Feb 27 2012, 02:06 PM)
Interested. Could you post a tut and perhaps info on how to add optical please?
For optical follow this guide: http://forums.xbox-scene.com/index.php?showtopic=596642
As you can see in that guide there are points on the bottom side of the av socket which can be used to add phono sockets to your console. However, the way I did it should give improved sound quality provided your audio system is capable enough of allowing you to hear a difference.
WM8521 datasheet:alldatasheet.com WM8521datasheet
The points shown on the motherboard are the nearest available without soldering directly to the pins of the DAC chip. These points are on the input side of the coupling capacitors. The purpose of coupling capacitors is to prevent DC voltage getting into your preamp. They are otherwise known as 'DC blocking caps'. Because the audio signal passes through these cap's on its way to your amp, their quality matters. Microsoft has gone with the usual Tantalum types which are fine but not as good as Film type capacitors where quality audio is concerned. Film capacitors give the best sound quality. Unfortunately Film caps are usually physically big, so I have used 'Wima MKS2 4.7uF'. You can use anything between 4.7uF and 10uF - voltage doesn't matter. But I recommend the Wima's as they are quite small in size as far as film caps go. I have used them in audio gear as a upgrade and they always bring the sound quality up a notch.
If you dont want to upgrade the coupling caps then take your signal off the other side of the existing caps. Simply solder to the av connector side of the existing coupling capacitors. This is a convenient topside point to solder to and still has the benefit of bypassing the unnecessary filtering circuits etc....
In my mod I lifted the tantalum caps to break the circuit to the av port. You dont need to do this but I did it to keep the audio signal as pure as possible. When you pass audio signals through many junctions, filters, components, connections etc it degrades in quality. The way I have done it above it comes right off the DAC via good quality caps and straight to the RCA phono sockets. In the existing scheme audio passes through various (unnecessary) components and connections before reaching your amp. There are filtering circuits on the 360 motherboard which aren't required, as the WM8521 already has them built in. See datasheet.
Last but not least, we now have proper RCA jacks on the back of our 360 so we can use a decent quality phono cable and get that delicate audio signal to our amp with as little degradation as possible. For cable I reccomend Canare LC-1 as a cost effective good quality cable. Their plugs are rather good too. Blue Jeans Cable
Did I mention im an audiophile? lol! Thats my other hobby. I have built amps and modified the hell out of CD players and speakers etc. I built this a while ago:
Next up I want to look at how MS designers have decoupled the voltage supply to the DAC chip as this is an area that matters immensely in audio. Looking at the datasheet, Wolfson has recommendations for how it should be done. So we can try to implement these with a couple of mods.