PC to headphone amp via DAC - whats the best interconnect method?

[admin_exported]

I have a media centre (Vista OS) with Realtek HD Audio.

I currently have the HDMI out connected to an AVR and sending video and audio.

I want to connect a DAC to my media centre and then connect the DAC to a Graham Slee Solo headphone amp to play lossless iTunes tracks and Spotify.

I think I have 3 options and seek your advice:

1) best Sound Quality (need 2 metre connect distance only) I believe is via Coax

2) Next is Optical (which would be best option over a longer cable distance)

3) Finally USB

My questions are these - does the Coax or Optical output work with the HDMI connected or can you only have one output connection only?

If I can have two output connections, do I have to make changes in the Realtek interface depending on which output I want to use?

Many thanks

 

[idc]

I dont know your equipment, but if any kit has more than one digital connection, whether it is HDMI, USB etc then it can shurely handle more than one input at a time.

As to which is best, coax, optical and USB, the debate rages on and there is no clear winner. In fact there will never be a clear winner as different kit implements the different connections in different ways, so what may be best with one, may not be best with another. I do not know of any maunufacturer who provides more than one type of digital connection and then recommends one over the other. You would, for cost reasons, be best to keep the digital connection longer than the analogue from DAC to the Solo.

I have no idea about Realtek, sorry.

 

[Anonymous]

To get a better picture of your system, is the Realtek HD audio on your graphics card (recent NVidia GeoForce 9xxx or ATI Radeon) or is it on the motherboard with a two wire cable going to a connector on the Graphics Card.

I have a Realtek ALC888 on the motherboard and a PCI GeoForce 8400GS with HDMI output (albeit with a DVI connector just to confuse people). This graphics card has no audio controller but it does have a spdif-in connector so i can send SPDIF from the motherboard spdif header to Graphics card and out over HDMI.

SPDIF output is just a two wire signal/ground affair and providing the digital output is strong enough it is possible to split the signal as I have done, so I can simultaneously send SPDIF via HDMI and also via a teflon insulated phono socket which I connected to the outside of the HTPC case which feeds an external DAC. The SPDIF HDMI audio just outputs via the LCD television (if I wanted it to).

Also with the Realtek HD Audio codecs, even if the HTPC is configured as a 5.1/7.1 system, it only ever sends 2 channel PCM via SPDIF unless you enable SPDIF passthru in your playback software such Power DVD.

The only other thing for two channel PCM playback is to ensure the HD audio chip is clocked at 44.1 but even when left at this clock setting, the SPDIF passthrough of 5.1/7.1 should ignore this.

The Realtek HD Audio codecs also tend to be bit perfect as well (providing no Equaliser/DSP effects are enabled) which makes them a cost effective way of feeding 2 channel high quality DAC.

 

[Anonymous]

Thanks, my Realtek HD adio is on the graphics card (NVIDIA GeForce 9500 GT).

Looking at the back of the PC I can see red light from the SPDIF socket, so assume that this means that it is active whenever the PC is on? So I guess that a connection from here to the DAC would be operational. I just don't understand if I need to make any changes depending on what source I want to output to.

In other words if the AVR is off and the DAC is on would sound automatically go via the SPDIFout to the DAC?

Then if I wanted to output sound to the AVR do I just switch the AVR on and sound and video would automatically go via the HDMI?

I looked at the DacMagic user manual and there is a good explanation of how a USB connection type works, so at worst I can go this route.

Preference would by optical or coax though.

 

[ESP2009]

If it's any help, I have USB from my laptop (or tower PC on occasion) to the DACMagic on the other side of the room. I use a standard 5m USB and one of those 5m booster USB cables to get from one to t'other. The sound is great. I believe it is a clear improvement over the standard quality audio lead I originally ran from computer direct to amp.

I'm afraid I can't really help with anything else.

 

[Anonymous]

Thanks ESP2009.

Good to know. Can you tell me, if you power off the DACMagic does audio control hand back to the PC or laptop soundcard?

Regards

 

[ESP2009]

sillyoldman:

Thanks ESP2009. Good to know. Can you tell me, if you power off the DACMagic does audio control hand back to the PC or laptop soundcard? Regards

A very good question. I had noticed at work that when using my iBasso D2 Boa headphone amp that both Spotify and iTunes get stroppy if you don't plug the USB in before they are invoked, and also do likewise when you unplug it whilst they're running. I very briefly tried the same with the DACMagic before leaving for work this morning - same result.

Short answer: No. Longer answer: maybe someone with better knowledge can provide information on a setting that avoids this.

Sorry I can't be more helpful at this point.

 

[Anonymous]

Given that you have a SPDIF socket with red light at the back of the PC, this would imply you have onboard sound as well as the HD audio controller on the Graphics Card, so under the playback tab of the Control Panel > Sound in Vista you should see two digital outputs, one feeding the AVR via HDMI, and a second which can feed the DAC and is linked to the analogue speaker output.

If you use the DacMagic USB connection, then you are effect adding a third digital output to this list. This is why
ESP2009 has problems using his DACMagic with Spotify/ITunes as they only use the default audio control (green tick) in the Playback list. If the USB DacMagic is switched off, then they will use whatever is left in the list of playback devices, so he will not hear sound as the DACMagic must be set as the default playback device if that makes sense.

If you are just going to be listening to 16bit sources (the maximum bitrate the DacMagic accepts via USB), then the USB connection is probably the best connection to use as jitter should not really come into the equation, although try the SPDIF TOSLINK option as well any jitter in this connection may even improve the sound, and it will allow to send 24bit data although you will need to make sure the SPDIF is set to the correct sample rate (44.1khz for CD sourced music).

 

[Anonymous]

Thanks to all for your suggestions and ideas.

I have today bitten the bullet and connected the DacMagic to the SPDIF socket on the PC and as digital connection 1 on the DAC at the other end.

It works beautifully and the sound is glorious. I have just experimented with the AVR on as well which powers my home cimema speakers.

I can get audio actually playing through both headphones and speakers simultaneously (alhough not a requirement). Muting the PC kills the speaker output and leaves the DAC and headphone amp working. So in routine use the AVR will stay off for audio listening.

All I need to do it seems is to alter the signal output from the Realtek HD audio manager from Dolby Live (5.1) to one of the other choices (CD quality up to studio quality) when using the DAC/headphone amp.

I'm really pleased it has worked out this way as it is exactly what I was hoping to achieve.

Once again many thanks for helping me out. I am a very happy camper.