..If I was more gaming orientated, I'd be best to go for something from Asus or Creative with SBX?..
SBX is better for gaming. Dolby Headphone was designed for movies, which is to be expected, given that's what Dolby do. Having said that, it does work well for gaming and some people may prefer it over Creative's SBX. In general though, I think most people would say SBX is better for gaming. Dolby can have more of an echo effect, which puts a few people off it.
Of course though, getting one device with SBX that can drive headphones such as the HD650, is not cheap by any means. For a start, HD650's don't make the best gaming headphones, so to spend £200 on a sound card that's capable of driving them, just to get SBX, doesn't make a lot of sense; not to me anyway. Not when your first priority is music.
For those who prioritise gaming, HD599's and a SB Z, is a better choice. £200 cheaper than HD650 + ZxR and will also have a good sound for music.
Although a Schiit stack costs a bit more. It's a better long term solution for the HD650's and other headphones in need of a good amp. Sound cards are too reliant on other factors, such as working drivers; Windows updates not causing sound issues; no electrical interference affecting the sound card. Whether such problems are common or not, they do happen. If you spend £50 on a sound card, it doesn't matter too much if that is affected by any of those. Spend £200 though, then that's a different story. A DAC and the connected amp are completely separate, so not reliant on software and drivers; and if using optical, will be decoupled from the PC electrically.
You can always add a Soundblaster Z for £60 at some point, if you want SBX. As long as you have a DAC with optical input, that will work. Best to try Razer's software first though, because it might be something you're just not fussed about. In which case, the thought of spending £200 on a ZxR, really would be a waste.
Not everyone likes these headphone surround sound effects. Some people don't and prefer stereo with no effects.