On 24-04-08 21:13, Matt Garman wrote: > In short, I'm looking for the best stereo sound I can get from my Linux > system---the main use will be listening to my CD collection (ripped as > FLAC). > > A specific question: if using digital output, is there a difference > (sound quality-wise) between optical/toslink and coaxial? Say my > soundcard can output both via optical and coax, and my amp also supports > both inputs: any reason to choose one over the other? Distance is the important metric -- really the only one. If you have to bridge a few metres you're going to get bitperfect results 100% of the time from just about anything non-broken and you needn't worry about it while with increasing distance you would start to pay a little more attention to cable. Original TOSLINK is specified at upto 10 metres (and used to be adviced at no more than 5) and while this is fully dependent on the actual cable used, good long cables get expensive to really expensive. With coax you should at any length make sure it's 75 ohm (it always is if it's specifically a digital audio cable). The longer it is the more chance of picking up (RF) interference so you want it to be progressively better shielded. Optical, not being electrical, does not pick up electrical interference and is as said not susceptible to ground loops due to that same reason which can make it a good choice. Optical is more fragile and if you have to bend it around too many corners reflections could be a problem. Really sharp bends won't do period. Optical as said also needs/wants expensive cable sooner than coax. Basically, "digital is digital" is indeed exactly what it is but at least when reconstructing the clock from the S/PDIF signal cable induced jitter occurs when the fairly square wave the 1's and 0's leave the transmitter as have degraded into rounded square waves enough that the receiver gets timing problems reconstructing the exact clock. These days the receiver actually usually reclocks itself anyways though (exactly due to this issue) and then it all makes even less of a difference. Optical used to have a somewhat bad reputation but in the absence of actual breakage you need pretty serious reflection problems to get non bitperfect results. That said, I'd probably pick coax for most setups where ground loops are not an issue if given the choice. > Also, if I'm looking at pure digital output, is there a quality > difference between sound card models? My understanding is quite naive > (and certainly incomplete!) but it seems like if the software (flac123, > mpd, whatever) converts the FLAC code to a digital audio signal, the > sound card doesn't really have any work to do. ... except clocking the data out. Stability of the clock is a bit of an issue here but it's again only marginal when your receiver isn't in fact extracting its clock from the signal. > In other words, my motherboard (Abit IP35 Pro) has an optical SPDIF > output for its Intel HD Audio system. Would this be any > better/worse than, say, a Chaintech AV-710 with optical out (which > I'm using in another PC), or an MAudio Audiophile 2496 coax SPDIF > output? > > My understanding has always been that "digital is digital", but > after doing some reading today, I'm not so sure that's true. As with most things in audio, the trick is to do more listening than reading... Rene. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
