My motherboard is just the ASUS® P8Z77-V LX: USB 3.0, SATA 6GBs, ATI®CrossFireX.
Id rather not have to spend any more on an upgraded sound card then if there is not much difference. Im only going to be using stand alone speakers which cost about £30.
All the recent ASUS mobos (motherboards) actually have - relative to other companies' mobos - excellent integrated sound. Either way you're very unlikely to notice the difference with those speakers.