most people wont benefit using a USB connection for wireless headphones.. because as you suggested, the soundcard cant use it's processor to keep your frames per second high.
just because the headphones have a digital decoder, that doesnt mean there is a data processor to take the load off of your cpu.
with that said..
maybe you can send the audio data to the soundcard normally.. then use any of the various audio data 'routers' and route the data to the usb soundcard.
see.. there are directX programs that will let you do it.
these are usually called a 'directX host' that most often is used to route VST plugins.
i dont think it has to be directX .. could possibly be whatever program language known.
the problem is, programming one yourself or finding one already made.
and also, finding one that will work with everything without any problems or conflicts.
try 'virtual cable' and see if that works for you.
it is a program that is really simple.
you let the video game send the audio to the soundcard as normal.. but then use 'virtual cable' to grab the output from the soundcard and send it to the USB soundcard.
all this does is allow your pci (or pci-e) soundcard to use its processor to keep the load off of your main CPU so that the game runs faster (more frames per second)
but
maybe this will clog your southbridge and your frames will go down 5 or 10 per second.
it is certainly a lot better than losing HALF of your frames per second because you are using a USB soundcard.
i switched from a pci soundcard to the onboard soundcard and my frames per second were down from 80's to ....
i really dont remember if it was 60's or 40's
all i remember is that it was a huge chunk that proved my soundcard being installed helped the game run faster, much like it was advertised to do.
virtual cable will work with asio and asio4all to keep the data transfer quick and without degrading the quality.
when you use asio from the pci soundcard to the usb headphones.. you might be able to get a transfer time all the way down to 1ms
the website says it will work anywhere from 1ms to 20ms per interrupt
and 1 - 100 pins.
it supports kernel streaming too if you dont want to use asio (or asio4all)
the wireless signal is very fast, so you wont notice any latency added there.
creative and logitech has failed on me way too early in the past.. so maybe try the turtle beach headphones ?
i mean.. just look at the specs of the turtle beach headphones..
first of all.. they are dolby certified for localization.
they have a bass boost of +9dB for anything from 20hz - 150hz
that is a HUGE plus to have a bass boost that low, if not for explosions in games.. it is fantastic for movies and music.
the drivers are 50mm .. and in the headphone industry, that can be like the difference between some 10 inch subwoofers compared to some 15 inch woofers.
(if you dont know the difference, the bass gets lower with the 15's)
the microphone is a condensor type, and condensor types are known for their flatter frequency response.. they are much more sensitive and accurate, plus the mic says it will go down to 50hz ... unlike the logitech's 100hz (big difference)
the specifications say the headphones are up to >120dB
and that means, for a fact, the headphones have bass.
otherwise 120dB would be more than putting your ear 1ft away from a DJ speaker !! and that just isnt going to happen for liability reasons.
the only problem i see is the 48khz sample rate.
but
dolby digital on DVD or video games dont really get any higher.
video games might get higher, but DVD's wont.
the headset says it can use batteries for up to 25 hours.. and that means the batteries should last for 2 days and re-charge overnight before you go to bed.
the website says the connection is an optical input.. and that means you dont have to mess around with 'virtual cable'
but
it does get power for the amplifier from the USB socket.. and at only 180mA current draw.. the amp doesnt pull much from the usb power supply at all.
the usb power output has a maximum of 500mA
even the name 'turtle beach' sounds like an audiophile company.
besides.. i already know, soundblaster with their EAX and cmss 3d sounds like junk compared to dolby virtual surround sound for headphones.
i see the creative headphones are bragging about sounds above and below you.
maybe the turtle beach doesnt do above and below (never ever heard 'em)
but
the dolby technology does the 360 around you much much better.
and since most games dont have above or below sounds anyways.. you dont need it.
to finalize, it says the creative headsets last 9 hours and the turtle beach last 25 hours.
you can always go on ebay and get some AAA batteries with a higher 'mah' rating.
the higher 'mah' rating usually means they will last a lot longer before going dead.
you can find some decent sized 'mah' batteries at walgreens.. but ebay has the much higher ones.
i am wanting to hear the turtle beach headphones myself.
the bass boost and the stereo expander should really be two simple things that get the ball rolling quickly for anybody.
and even if the sound quality isnt 'audiophile' but still good.. the battery life and the bass boost, and stereo expander, and bigger 50mm drivers, and headphone stand, and better visual aesthetics, and dolby 7.1 (not 5.1)
seems like these things are selling themselves.