[zdogg]

I recently decided to FLAC encode many of my CDs and I want to make sure I have bit perfect output using Foobar with the Chaintech AV710, Optical out to Benchmark DAC1. I am currently using VIAs v324 drivers. Using Mr Radars setup guide I use Kernal Streaming, 24 bit padded to 32, with 96k resampling and it seems to work.

I wonder, though, if this is bit perfect, unaltered digital output. I don't really need resampling because I'm feeding the DAC1. Am I using the right setup or is there a better way to achieve unmolested, bit perfect output from the optical out?

 

[Glassman]

if you're using just digital output, flash the card for some more professional one, you get much better drivers with ASIO support and 100% bit perfect.. search for 'flash chaintech prodigy'..

 

[rincewind]

for starters, if you're after bit perfect audio, you shouldn't be upsampling. keep it at 44.1 for normal cd audio

 

[zdogg]

Quote:

Originally Posted by rincewind for starters, if you're after bit perfect audio, you shouldn't be upsampling. keep it at 44.1 for normal cd audio

Right, I figured that but for some reason, Kernal Streaming won't output unless the resampler is enabled and set to 96K. That's why I need another approach other than KS. I've heard that waveout and Directsound may not produce bit perfect output.

I may try flashing the drivers as Glassman recommends (thanks!), but is there any easier way with the current drivers I have?

Interestingly, I compared a FLAC I ripped using playback with foobar/waveout/no resampling/optical/DAC1 to the original CD via Panasonic DVD player/Zu ASH coax/DAC1 and the CD original sounded subtly better (greater clarity/air/base extension). Wonder if the weak link was the foobar flac encoder, the waveout output, the optical line out, or all of the above

Oh well, I'll start by trying to get bit perfect output...

 

[Dixie Flatline]

Quote:

Originally Posted by zdogg Right, I figured that but for some reason, Kernal Streaming won't output unless the resampler is enabled and set to 96K. That's why I need another approach other than KS. I've heard that waveout and Directsound may not produce bit perfect output.

When you use KS, all audio sent to the soundcard has to be in a format natively supported by the soundcard, since you're bypassing KMixer, which normally resamples to a native format (and affects the sound quality in the process). When you set the AV710 to hi-res mode, it only supports a native format of 96KHz/24-bit, which is why you need to use the resampler.

However, the only reason to use hi-res mode is so you can take advantage of the high-quality Wolfson DAC on the card's rear outputs. Since you're using an external DAC, all you should need to do is turn off hi-res mode, turn off resampling in Foobar, and use kernel streaming to send the unmodified 44.1KHz data to the card (which does support this format when not in hi-res mode), which will pass it out to the DAC-1. The difference you heard in your test was probably due to the resampling done in Foobar, which is unnecessary in your case.

 

[zdogg]

Quote:

Originally Posted by Dixie Flatline However, the only reason to use hi-res mode is so you can take advantage of the high-quality Wolfson DAC on the card's rear outputs. Since you're using an external DAC, all you should need to do is turn off hi-res mode, turn off resampling in Foobar, and use kernel streaming to send the unmodified 44.1KHz data to the card (which does support this format when not in hi-res mode), which will pass it out to the DAC-1. The difference you heard in your test was probably due to the resampling done in Foobar, which is unnecessary in your case.

Outstanding! I took your suggestion and now KS works great at 44.1khz. Thanks! Now my last question is, what should I set the output bit depth to (currently at 32bit fixed)?

 

[Dixie Flatline]

Quote:

Originally Posted by zdogg Outstanding! I took your suggestion and now KS works great at 44.1khz. Thanks! Now my last question is, what should I set the output bit depth to (currently at 32bit fixed)?

If all you're playing is 44.1KHz/16-bit audio ripped from CD, then I would think just go with 16-bit fixed output. As I understand it, setting it to a higher depth would just pad the data to the right length with zeros in the least significant bits, so it shouldn't make any difference in the sound quality -- the DAC-1 will do whatever upsampling or oversampling it wants internally. So I'd keep it at 16-bit unless you're playing files with a greater bit-depth in Foobar, which shouldn't happen very often, if at all.

 

[Glassman]

or in case you're doing volume control or replaygain.. leaving it at 24bit padded to 32bit is the best you can do..

 

[Dixie Flatline]

Quote:

Originally Posted by Glassman or in case you're doing volume control or replaygain.. leaving it at 24bit padded to 32bit is the best you can do..

Ah, good point. (Of course, if you're doing anything to the signal in foobar, then it's no longer technically bit-perfect with the original signal, but I should think it's still worthwhile.)

 

[zdogg]

Thank you guys. I probably will end up using Foobar's volume control because I may try Iron Dreamer's mod (using a balanced cable out from the xlr outputs on the dac, using Foobar volume instead of the onboard volume pot). Will 24 padded to 32 be the best option (even if not technically "bit perfect") in that case?

 

[KyPeN]

I literally just came to post a question on how to do this with the modded AV710 to a Prodigy, and now I get bit-perfect 44.1, thanks big guys!

 

[remilard]

I still can't get kernal streaming to work w/o resampling in foobar. In the envy control deck I have high quality mode unchecked and I am not using resampling in foobar per above post, I still get a "cannot open output device" error. Any ideas what I'm missing?

 

[Dixie Flatline]

Quote:

Originally Posted by remilard I still can't get kernal streaming to work w/o resampling in foobar. In the envy control deck I have high quality mode unchecked and I am not using resampling in foobar per above post, I still get a "cannot open output device" error. Any ideas what I'm missing?

See the last post in this thread. If you've got "PCM and AC3" enabled in the Via control panel, turn that off too.

 

[remilard]

Quote:

Originally Posted by Dixie Flatline See the last post in this thread. If you've got "PCM and AC3" enabled in the Via control panel, turn that off too.

I have "pcm only" checked in the control panel, I am assuming that is correct?

I think I might try uninstalling and reinstalling foobar and just setting everything up again, I may have messed something up that I can't find.

 

[Harrath]

I hate to commit forum necromancy, but does the AV-710 support bit-perfect output without the flash to the prodigy?