Who wants to be an Audiophile?: The best computer audio playback software (updated)

Jump to the bottom of this post to the 27/07/13 update for the latest developments... there is a new player in town, and it beats everything!

Screen shot of cPlay GUI

I will qualify my comments below by saying that I am presently using a USB Spdif converter, and so my comments are limited to using this output device. Perhaps results will be different if using a PCI soundcard to output the SPDIF signal?

I use cPlay with CMP to play back my flac and wav files. http://www.cicsmemoryplayer.com/

The sound quality can be very very good, but setting it up can be fiddly, and one wrong change to a registry value can completely ruin the sound. You can go from, totally amazing sound to very underwhelming sound with one minor registry change. CMP sounds great when you manage to set it up well. For those who only have one PC and are able to dual boot, this is my pick for the best Windows audio software.

Another very good playback software is Vortexbox http://vortexbox.org/content/123-downloads

Vortexbox does not have to be used as a streaming server. It can be used as a stand alone player -except for that you will need to control it either from another PC, or by using an app on a mobile phone, or pad.

You can use a USB to SPDIF converter with Vortexbox, but you are limited to devices that will run using the Linux ALSA driver.

Vortexbox straight off the bat, sounds very open and balanced. Bass goes very low and highs are very extended and open sounding, with lots of detail presented in a non fatiguing way.

In comparison, CMP with cPlay, when set up well, sounds quite a bit darker, and thicker, but it also sounds more dynamic. Bass goes deeper and highs go higher on CMP cPlay. But either one is very good.
CMP is still my favorite, but I need to see if I can extract any more from the Vortexbox before further comment.

Update 28th November 2012
A friend of mine who uses CMP with cPlay tried Vortexbox and he said that he prefers the sound of Vortexbox.

I will also add that I have tried a couple of different software such as Stealth player, XXXHighend, Album player, and probably some ones that I can think of right now... but still from my point of view the two best sounding players are CMP with cPlay and Vortexbox.

The major advantage to Vortexbox is the ability to control it with an Apple or Android phone or pad.
For those seeking convenience, this is a no brainer - Use Vortexbox.

Update:
Possibly the best playback interface is the Yellowtec PUC 2. See my review here!

Vortexbox installer GUI

Update: 27/07/13

If you have windows 7 or 8, you MUST try MQn software. It is under constant development. The latest version sounds quite amazing. It beats CMP +cPlay by a big margin. It is smoother, more detailed, and has bigger cleaner bass. I didn't think computer audio could be this good.