sorry took so long for the update
first off never use computerwebstore they are a complete joke ordered on the 10th and they only shipped today i had already got bored of waiting and ordered off amazon so providing they do actually turn up tomorrow i will be selling a set on amazon so should get most of my cash back!
right now to the headphones lol, first off let me state i havent tried on an xbox 360 yet so havent got a clue about game chat etc.
i have been using these on my dvd player with optical out.
these headphones absolutely trounce the sharkoon headphones i had there seems to be a lot better sense of direction with these and the sharkoon v2s sounded tinny in comparison.
these have a bass boost function but i leave it turned off as you lose some of the high frequency and i honestly dont think it needs to be on there seems to be ample bass with it left off.
they have a stated battery life of 20 hrs but havent ran any batteries flat i have just bought 4 rechargeable aaa batteries and swap them after 5 films this way there should always be enough juice to run these bad boys lol

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right now the only negative aspect is the slight hiss which you get with most infrared headphones but to be honest you soon zone it out and its only really noticable at all on really quiet scenes.
i cant comment what they are like with plasma tvs as i dont have one but ive seen people stating they are ok as long as not sat too close so this is a gamble your going to have to risk if using with plasma screen.
so to top it off i would say im happy with my purchase minus the whole having to mess around with computerwebstore but that looks like its sorted now