[Seaside]

Setting aside all those fancy stuff a soundcard can offer for a while.

As far as I know of, simple USB dac like alienDAC is not supporting directX acceleration. Even if it supports directX acceleration, I assume it's not as fast as what X-fi processor can do. Also, USB 1.1 chip like PCM2702 can not transport/process messive amount of sound data X-fi able to handle, i think.

Is that means you're going to sacrifice gaming performance when you use USB dac instead of X-fi? Can USB dac cause decrease of FPS or jittery mouse movement while in gaming?

Thanks.

 

[milkpowder]

I have really never come across any real-world, appreciable difference from using USB DACs. You may very well have a slight decrease of fps but that shouldn't make a game any less enjoyable/playable.

 

[FallenAngel]

"Slow down" games no. Not work as fast as an X-Fi, definitely, but real life difference is maybe 5%, and that's REALLY stretching it. Hardly anything you'll notice or miss.

As for transport/process "massive" amounts of data, you don't need "massive" by any stretch of the imagination. USB 1.1 at 12mbps is more than you can ever use for audio streaming.

 

[Seaside]

Here's my original thought.

CPU is going to throw sound data into sound device. If sound device can process the data without any problem, the sound will be nice and smooth. If there's any problem, sound device try to correct it. It may request the data again. CPU may send the data again, whole process may start again. I thought that's why some soundcards slow game down. But USB dac is not doing this feedback/replay routine.
Thus, USB dac should not slow game down.

Well... that's just a thought and someone know better may tell me some details for me.

Anyway, it is good to hear from you guys that USB dac is not slow game down in real life. I think I can safely use USB dac without worrying too much.

 

[FallenAngel]

Sorry, your thought is wrong because there are no "problems" that occur and nothing gets "sent again" or reprocessed.

Sound cards like the X-Fi have built-in memory and a processor which handles audio duties (mixing different sounds in games, positioning, etc) - generally called hardware acceleration. If there is no processor to do this, the CPU does (as what happens with DACs and soundcards meant for music/recording).

Yes, you can safely play games with a USB DAC, but you'll be missing out on the cool little features like OpenAL, CMSS, EAX, etc.

 

[Seaside]

Thanks fallenangel.
I assumed there must be some sort of feedback or correction b/w CPU and sound device, and it seems not what is going on.