[ljbrandt]

I need some help...
 
I have a Yamaha RX-Z9 A/V receiver that I'll be using as a DAC/amp with a computer desktop setup.  The amp accepts toslink/coaxial digital inputs up to 24/192k.
 
Question 1: Would it be acceptable to just connect my PC's MB's toslink output direct to the Yamaha or would an investment in a usb interface (i.e. SMSL x-usb) in between the PC and amp yield a significant improvement?  
I will be using the Yamaha's DAC either way, so I'm skeptical about how much sonic benefit there would actually might be.
 
Question 2: If the interface is the way to go, which is recommended?
 
Question 3: Coax or optical for the interface to a/v receiver and why?
 
Thanks

 

[obobskivich]

1. No, there will be no benefit - use the built-in, and you may give up significant features. Most of those "USB interfaces" are bare-bones basic in their functinality, while many modern PCs support not only relatively high resolution PCM output like 24/96 or 24/192 (note that there is ZERO benefit to sending 24/96 out if you aren't sending 24/96 data), as well as real-time multi-ch encoding (e.g. DTS Connect or Dolby Digital Live) which can send a 5.1 signal out (this is really only useful for gaming).

2. No. See above.

3. Does not matter in general - use whatever is common (the Z9 has many more TOSlink inputs than coax inputs). TOSlink is immune to ground loops and RF interference, but I wouldn't start from the assumption that such a thing will be a problem (e.g. don't go out buying up things, trying to solve problems you don't know if you have or ever will have). Just make sure you do not use the "LD AC-3 RF" connector on the Z9, as that is not an S/PDIF input; its an RF input, intended for the RF output of certain Laserdisc players. It also does not matter which labeled input you select - they're all "equal before god" in the Z9's eyes.

3a. If you have a multi-channel soundcard you may also consider sending out an analog signal to the multi-ch input on the Z9, if you're wanting multi-channel audio for gaming (especially if the soundcard does not support multi-ch encoding, like DDL/DTS:C). This could be done "in addition to" a digital connection, if you still want to retain DSP features on the Z9.

 

[ljbrandt]

Thanks for the advice, although the USB interface I'm referring to is the newer SOTA XMOS boards based on the new XU208 receiver chip.

 

[obobskivich]

Thanks for the advice, although the USB interface I'm referring to is the newer SOTA XMOS boards based on the new XU208 receiver chip.

Is this supposed to make me do some wild backflip?

If a USB device is going to support very high bitrate output, at least in Windows, it means 3rd party drivers to implement it. So you're taking your chances with whatever no-name manufacturer's hastily slapped together driver from the chipset manufacturer's SDK, and hoping it doesn't cause problems with your system. And it still won't do anything magical or mythical for you, as long as your S/PDIF source isn't pumping noise into the output (e.g. from a noisy line-in).

 

[ljbrandt]

Is this supposed to make me do some wild backflip?

If a USB device is going to support very high bitrate output, at least in Windows, it means 3rd party drivers to implement it. So you're taking your chances with whatever no-name manufacturer's hastily slapped together driver from the chipset manufacturer's SDK, and hoping it doesn't cause problems with your system. And it still won't do anything magical or mythical for you, as long as your S/PDIF source isn't pumping noise into the output (e.g. from a noisy line-in).

You have a point about the drivers, but there's like a 250 page thread here on head-fi about these new usb interface boards.
My intention is to start with the realtek optical out of the PC directly to my A/V receiver with a glass toslink cable and see how that goes...

 

[PurpleAngel]

I need some help...
I have a Yamaha RX-Z9 A/V receiver that I'll be using as a DAC/amp with a computer desktop setup. The amp accepts toslink/coaxial digital inputs up to 24/192k.
Question 1: Would it be acceptable to just connect my PC's MB's toslink output direct to the Yamaha or would an investment in a usb interface (i.e. SMSL x-usb) in between the PC and amp yield a significant improvement?
I will be using the Yamaha's DAC either way, so I'm skeptical about how much sonic benefit there would actually might be.
Question 2: If the interface is the way to go, which is recommended?
Question 3: Coax or optical for the interface to a/v receiver and why?
Thanks

That's a fairly high end (but older) A/V receiver, guessing your looking at spending a lot more then you would like, with getting an external DAC (USB, optical, coaxial), to try to improve audio quality, over the RX-Z9's built in DAC chips.
Better just stick to an optical cable from the computer to the RX-Z9.
S/PDIF (optical or coaxial) will normally carry up to 2-channels of PCM (un-compressed) 24-bit/96k or 24-bit/192k digital audio, if you want to send more then 2-channel, like up to 6-channels (5.1) you will need to encode/compress the audio, using DDL (Dolby Digital Live) or DTS-Connect software, max 24-bit/48k, unless your playing a modern Blu-ray action movie or very special high res music audio, your not going to really notice a difference being limited to 24-bit/48K (for 5.1) Your motherboard might have come with Dolby or DTS software.
If not an Asus Xonar DG or DGX sound card, is a low cost way or adding Dolby software.
Coaxial is not as common on sound cards, like optical is, doubt you would notice a difference, between optical or coaxial.

 

[ljbrandt]

Thanks PurpleAngel

I think the S/PDIF output of the PC will be just fine as well, especially when using a good glass fiber cable. The only thing that has me 2nd guessing myself is what I've ready about jitter and clocks and timing and all these type things. That's what led me to ask the question to begin with.

 

[PurpleAngel]

Thanks PurpleAngel

I think the S/PDIF output of the PC will be just fine as well, especially when using a good glass fiber cable. The only thing that has me 2nd guessing myself is what I've ready about jitter and clocks and timing and all these type things. That's what led me to ask the question to begin with.

I'm not against you buying USB DACs for trying to improve audio quality, It would be nice to have you experiment and post back the results, just depends on how much spare cash you want to use.
And if(?) you get no noticeable improvement, are you ok with that (after spending the cash).