Gaming audio - Dolby Headphone, positional 7.1, mix amps, what?!

While shopping for a new gaming headset, I've come across a lot of different technologies and different ways to use them to get the best sound of your games. Being the clueless soul I am, maybe you guys (and gals!) can help me out here:

1) Do all headphones support Dolby Headphone technology?

2) Positional 7.1 surround sound - Can an ordinary pair of cheapo headphones support this?

3) What would the benefit be (or not) of using an Astro Gaming mixamp (like that found with the A40) with a PC outfitted with a Creative X-Fi Titanium Fatality sound card? Is the use of the mixamp wasted in this application?

4) Is a headphone that uses USB really an audio sin where audio quality and perfomance is concerned?

5) Are headphones with muliple drivers/speakers (Razer Tiamat) better for producing surround sound than headphones with one single Left and Right driver/speaker (Audio Technica ATH-AD700)?

 

1) With the appropriate sound source, yes.

2) Yes. The key major difference from headphone to headphone is how well they can represent the 'ideal head' HRTF model of the standard CMSS / THX / Dolby Headphone model. This is further complicated by the fact that not everyone responds in the same way to the 'ideal head' model, since it's an averaged head. No-one has an averaged head (well one guy might out there, who knows). The way you perceive CMSS / THX / Dolby Headphone depends not just on the particulars of the headphone but also on the size of your head, how well you have the headphones fitted, how big your ears are and how your ear is generally physically configured, and all sorts of other factors - the effectiveness of virtual 3D tech like DH (Most virtual headphone audio) and CMSS/THX(Creative) therefore depends on how much you veer away from the average head that each solution provider uses to model the 3D sound delivery.

3) Unless you specifically need Dolby implementations the Creative cards IMO does positioning better from a gaming perspective, though good DH headsets can be really good. Asus's much-hyped Essence range is actually pretty poor in this respect IMO, despite apparently using unmodified DH models.

4) No. There's nothing wrong with the tech per se, although audiophiles might have some qualms about some 48/44khz resampling. It's just that they usually tend to be built down to a cost. When you get to budget levels like the better ~$100 USB headsets, their audio performance is equal to maybe a good $60~$70 closed headphone.

5) No. Whereas virtual 7.1 implementations try (with varying degrees of success) to create a 3D soundfield that isn't entirely in your head, the multi-driver headphones simply give you a) in your head left, b) in your head right, c) a bit behind left, d) a bit behind right, and e) in your head centre. And since each driver - including the main left/right - must be more compact to be shoehorned into the headset, they also offer poorer performance through any of their drivers compared to a regular two-speaker set.