Question about HTPC Sound Card

[WndrBr3d]

I'm currently in the process of upgrading some components on my HTPC, and while I was at it, I was thinking I would upgrade the sound card from the on-board audio to perhaps a AudioTek Prodigy 7.1

While doing some research, I came to the conclusion that in my case, it doesn't matter what sound card I'm using because I'm currently hooking my HTPC up to my receiver using Optical SPDIF.

I'm thinking this for two reasons:

1 - Since I will be mainly listening to music and watching movies, the DSP for the most part will be going unused because no effects will be added to the audio (Reverb, Echo, 3D, etc.)

2 - Since I will be using SPDIF out over optical, the DAC will go unused as well, since there will be no audio out over analog (or analog in).

So if my current setup isn’t going to be using the DSP or DAC at all (or very, very little), why would I need to invest in a high quality sound card?

Any help or input would be appreciated!

 

[SilverMK3]

Since you're mainly listening to music (2 channel) and watching movies (will have Dolby Digital already) then there's no need to invest very much... I suggest the Chaintech AV-710. It is very inexpensive, and has great 2-channel analog performance if you decide to use headphones some day.

If you were playing video games or listening to anything else that had non-Dolby Digital surround sound content, I'd suggest getting an HDA X-Mystique 7.1 Gold because it has a hardware real-time Dolby Digital encoder, which converts everything coming from your computer into a Dolby Digital stream. It doesn't sound like you need this feature, however, since would probably get better music performance when using uncompressed 2-channel LPCM streams.

 

[Audioholics]

I agree for the most part - you definitely want a card that has "Dolby Digital Live" which does the conversion to Dolby Digital in real time.

 

[WndrBr3d]

So the benefit of going with a card that encodes to Dolby Digital Live (X-Mystique for example) would only be for gaming that uses surround sound, this way I wouldn't need to run analog 5.1, but it could just encode the 5.1 out to DD and output to SPDIF, right?

From what I've read it seems that DD Live encodes a 6 channel stream at 640kbps real time (wow!). This would not be beneficial in a situation where I am listening to Music or Movies because it would only be transcoding the PCM stream and decreasing the overall audio quality, right?

While researching the X-Mystique, I decided to pull up some information on it's DSP (CMI 8768+) and was actually supprised when I found this diagram:

It shows how the SPDIF out strem will bypass the DSP and DAC all together.

 

[WndrBr3d]

Oh, that's dissapointing. It seems that the Dolby Digital Live encoding is done using the software/drivers packaged with it. So much for a hardware solution!

 

[SilverMK3]

So the benefit of going with a card that encodes to Dolby Digital Live (X-Mystique for example) would only be for gaming that uses surround sound, this way I wouldn't need to run analog 5.1, but it could just encode the 5.1 out to DD and output to SPDIF, right?

From what I've read it seems that DD Live encodes a 6 channel stream at 640kbps real time (wow!). This would not be beneficial in a situation where I am listening to Music or Movies because it would only be transcoding the PCM stream and decreasing the overall audio quality, right?

While researching the X-Mystique, I decided to pull up some information on it's DSP (CMI 8768+) and was actually supprised when I found this diagram:

[image]

It shows how the SPDIF out strem will bypass the DSP and DAC all together.

That's exactly right. The one caveat to the 640kbps bitrate vs. the standard 384kbps bitrate on DVDs is that there is a drop off in frequency response past 17KHz. This is was a decision made at Dolby Labs because there wasn't enough bandwidth to do 20Hz-20KHz at 640kbps.

The card can do Dolby Digital and DTS pass-through over SPDIF just like any other card with an SPDIF out. I believe that the encoding is hardware-assisted in some way because it is only available to this specific chipset, the nVidia nForce2 APU (SoundStorm), and the XBOX APU.

 

[WndrBr3d]

You're probably right in that it's hardware-assist, but in the benchmarks I've seen for the card, while playing in games such as HL2 or UT2004, enabling the DD5.1 out drops the game by about 10FPS, which means it's gobbling up some system CPU.

Thanks thought for the feedback and help!