I made a HTPC earlier this year. When I was offered to trade in my old Cyrus 3 for the 8XPd Qx I snapped the dealers hand off.
When I auditioned the system at the dealer I had bought 5 CD's as well as the same 5 ripped onto my laptop in Flac format using a program called Exact Audio Copy (EAC) in "secure mode" with AccurateRip. BTW if you need to rip a CD this is by far the best program I have found. If anyone knows of a more accurate ripper let me know.
The setup comprised of CD8SE connected to the analogue input. The CD player was also connected digitally to input 10 via co-ax. My laptop (Samsung Q35 XP SP3 with Soundmax HD audio) with was connected to input 11 via the USB.
While I noticed that the analogue input was slightly brighter and louder I could not really tell much difference between to two digital inputs. I synced the sources up and switched between the sources during playback and it seemed pretty seamless.
When I got my 8XPdQx a few weeks later I began to experiment a bit. I used Winamp as the main player as well as My HTPC (See spec at the bottom of the page). I noticed that when I played a 44.1 KHz Flac or MP3 the Cyrus displayed the right rate. When I played some of a few lower (32 KHz) sample rate the Cyrus still displayed 44.1 KHz. When to Music stopped in Winamp and "normal" windows system sounds where played in XP the Cyrus switched to 48 KHz. When playing video in Media Player Classic I noticed that the Cyrus displayed 48Khz with Xvid video embedded 48Khz MP3 and 41.1 Khz with 41.1 Khz MP3.
Now while I was quite pleased the Cyrus changed bitrate automatically I was always suspicious that the PC was and also performing some DSP algorithms therefore not presenting "bit identical" info to the Cyrus. My aim was for the Cyrus to expect the same info from my PC as it would from a CD8se. The fact that I could alter the volume control in windows shows that DSP is taking place.
Now quite a lot has been said about the pro's and cons of playing though a PC source but TBH nobody seems to address the main issues as in quite a lot of advise is given but it doesn't really nail anything down so here my attempt. For me the main factors for PC music are:
1/ The audio source and ripping method.
2/ The impact of your soundcard on your PC
3/ The ability to present "bit perfect" untouched signal to the Cyrus (I'll call it this from now on an 8XPdQx is a mouthful)
4/ The electrical interface (USB or SPDIF)
5/ Computer parts.
For me 1, 2 and 5 are fairly straightforward, 2 and 4 gives an element of personal choice.
1/ CD ripping I use Exact Audio Copy. I have been ripping CD's for over 10 years and I would say that this seems to be the most accurate ripper out there. EAC also checksums your rip with other peoples rips using Accurerip. Set EAC to rip in secure mode. I won't go into setting this up but I'll put a few links at the foot of the page.
2/ First a few things to clear up: Other threads on here have talked about soundcards being used when connecting to your Cyrus. This is not true. While using SPDIF you could say that you are using the soundcard but this only goes far electrical interface on the soundcard. I am not ware of a SPDIF-only PC card but you could use this with your Cyrus without a sound card at all. I can't prove this using the SPDIF but I can for USB. Turn the soundcard off in the BIOS on your PC or even take your soundcard out of your PC. The Cyrus amp will still work via USB because the PC sees the Cyrus as a soundcard. The quality of your PC soundcard for USB or SPDIF makes no difference since effectively the Cyrus is the sound card. You could say though that the quality of the USB or even then quality on the SPDIF interface on your soundcard could make a difference.
3/ Sound processing between your source signal to your soundcard, be it PC sound card or external sound card (your cyrus) is not "bit identical". This is because the way Windows processes the information to/from your soundcard. Windows XP uses Kmixer to mix audio from several sources. It does this by a combination of resampling and other DSP to combine signals. Prove this by turning on your windows sounds while playing music on your Cyrus. Widows has effectively resampled the sources and combined them. Even when you turn the system sound off it still processes. Proof of this is the playing 16 KHz sample rate music is presented as 44.1 KHz to the Cyrus. Further proof is the ability to alter the volume means DSP is taking place. While I'm not entirely sure that presenting a 44.1 KHz source with 100% volume would bypass this but I doubt it. Windows Vista and 7 has a better interface I'm pretty sure reprocessing take place since it will still mix from different sources. You also have the ability to set the sample rate of the soundcard SDIF (or Cyrus USB) which means upsampling in Windows 7 is taking place (not tried Vista). I am not sure with Mac OS but I'm sure DSP happens there too. Steinberg realised that this may be good enough for home PC use it was no good for audio professionals using PC based software. They produced software for their soundcards which bypassed "Kmixer" with "ASIO" providing bit-identical sound being sent to their equipment. The good news is there is software out there the does the same for your soundcard too as long as the soundcard had WDM drivers. You need to install a program called Asio4all which sorts the ASIO side of things out. You also have to install a pluggin for your media player to use ASIO. I am aware of a pluggins for Winamp and Foobar. I would like one for Media Player Classic and possible VLC player so if anyone out there who knows please reply. I tried ASIO on XP SR3 and Windows 7 and it works. The Cyrus now sees bit-identical streams. You will not be able to alter the volume level on XP or Winamp, only from the Cyrus.
You may decide after doing ASIO then there not much difference. I would recommend doing it in XP but the sound processing in Vista and Windows 7 is pretty good anyway. All I can advise is that you listen to the changes. If you play sounds from Winamp with ASIO the Cyrus will get a bit identical source. However if you play the same music from a different player say WMP it will revert to the windows interface. I've set my SPDIF in Windows 7 to output at 192 KHz. So when I play the music in WMP the Cyrus plays a 44.1 KHz upsampled in Windows to 192 KHz and the Cyrus locks at 192 KHz. When I play it in Winamp I get a 44.1 KHz bit identical source (which according the Cyrus is upsampled to 192Khz internally).
4/ USB Vs SPIDIF - I Try to keep this short. I've read several things on the internet about this and TBH I think there's so little in it it's up to personal choice. I'd tend to go on the side of SPDIF since it was designed for Audio. On the electrical side of things USB is probably a noisier interface than SPDIF but even with SPDIF there plenty of people out there who swear by co-ax and other by optical. You also have to consider the quality of the SPDIF on your soundcard Vs USB on your PC. I have only used the built in USB and built in SPDIF on my PC. Replacing this with a dedicated USB or soundcard with SPDIF will make a change remains to be seen. If anyone out there has done this then let me know if there was a difference.
The SPDIF connected on my inbuilt soundcard goes up to 192 kHz and only 48 kHz on the USB. SPDIF can send a 20 or 24 bit source as opposed to 16 Bit on USB. Theoretically the SPDIF has more fidelity but since CD sources are 44.1 kHz 16bits or DVD music 48 kHz then I can't really see the advantage unless you have a source higher than 48 kHz 16 bit.
5/ Computer parts.
I've gone for the HTPC option and I'm very please with it. I recommend a good quality PSU since is should be more stable and less noisy. Also go for a good quality motherboard, not necessarily the fastest one but one with better voltage stability. I have not tried dedicated USB PC cards or dedicated cards with SPDIF connections to know if you can get improvement there.
Program Links:
Exact Audio Copy
http://www.exactaudiocopy.de/en/
Accuraterip Pluggin for Exact Audio Copy
http://www.accuraterip.com/
Flac
http://flac.sourceforge.net/download.html
ASIO:
http://www.asio4all.com/
Wimamp pluggin:
http://otachan.com/ download
out_asio(exe)_070.7z (exe version) Ver. 0.70 (187KB) copy the 2 files held in the in
ormal or inSSE folder (if you have an SSE enabled processor) into the windowspluggins directory.
Tutorial Links
Eac Settings 1:
http://flac.sourceforge.net/faq.html#tools__eac_and_flac
Eac Settings 2:
http://www.hydrogenaudio.org/forums/index.php?showtopic=30959
How to set up ASIO: Rather garbled translated page but I manage it. Ignore their own software and read how to setup ASIO4ALL further down the page.
http://www.aqvox.de/Asio-USB-Audio-installation-e.htm
Reference Links
Cyrus 8XPd Qx showing that the Qx dac upsamples:
http://www.cyrusaudio.com/product.asp?ProductID=100&text=spec
Kmixer Info:
http://en.wikipedia.org/wiki/Windows_legacy_audio_components
SPDIF:
http://www.epanorama.net/documents/audio/spdif.html
USB:
http://en.wikipedia.org/wiki/Universal_Serial_Bus
USB :
http://www.planetanalog.com/showArticle.jhtml?articleID=12801995