Need a sound card that does DDL and DTS

[james.miller]

From what you are saying it sounds like my GTX 580 would be more than up to the task of outputting lPCM 7.1 channel digital surround sound over HDMI into my receiver right? Would this be preferable as DTS Connect and Dolby Digital are lossy formats?

Hi hughythomas, That is correct, the LPCM output should be the better of the two at least with modern games and from a quality of output point of view. The somewhat unknown quantity (to me, i dont have both to test this) is if LPCM over hdmi is worth losing the advanced eax support, for those games that support it,that you'd get from an x-fi using dd/dts encoding over spdif. You have both though, give it a go and see which you prefer. Dont assume LPCM is the right choice without trying both.

I work in pro audio so audio fidelity is VERY important to me...

I know, you said that already

Would there be little point upgrading to the HomeTheater HD from my Prelude as my GTX 580 could handle audio over HDMI to my receiver or am I missing something key?

Very little, I dont think the output from the HomeTheatreHD would be any better than your GPU.

I used my 5850 to pipe out 5.1 PCM sound to my receiver and it worked great. Only problem was Windows 7 and CCC saw this HDMI connection as a second monitor (my Asys 24" monitor is connected via DVI to the 5850) so it played havok with my fps in games. If you disable the monitor in display settings it also disables the sound!

Thats why I resorted to using my XFI Xtreme Music and SPDIF connection to pump out Dolby Digital to my AV receiver. tbh I cant hear the difference between PCM and Dolby Digital.

I forgot to mention, does changing the resolution of the hdmi output make any difference? I know with my onkyo 805 that i must have a video output from the hdmi on the gpu on order for the sound to work (i too have a 5850), but the resolution is not important - I wonder if something like 640x480 would claw some of that fps loss back.

EDIT: I dont like the look of this setup either: http://www.auzentech.com/site/images...t1_hthd_sm.jpg surely having your graphic piped through a sound card will add lag?

It would, yes, by how much I dont know though. I wouldnt worry too much; if you didnt notice the lag that your DD encoding introduces (and it does, trust me lol) then i doubt you'd notice the lag using hdmi passthrough to a sound card.

Oddly enough I saw your thread Elrasho - was going to bring up the issue of loss of FPS in a bit!

I can only assume that in the case of the HomeTheater HD, as we are dealing with DVI/HDMI (ie Digital connections) there should be noticeable lag...

Although this is entirely speculation based on the idea that all digital signals require clock sync

Any processing introduces lag. On pre-recorded media (ie dvd, bluray) this isnt a problem as you'd just delay the video by the same amount. With gaming you cant do this. It stands to reason that, all things being normal, lpcm output is the last cpu-cycle intensive output after analogue, with any type of heavy encoding obviously coming worse off.