Anyone have any sound card recommendations now for a Music Server PC? I'm thinking about building a music server from an old PC build. Thanks in advance.
Dean, Asus Xonar Essence STR and Creative ZXR are among the best consumer PCI audio cards. ($300) Whether these are good enough for audiophile use I don't know, they are targeted to high end video gamers. But there have been audiophile reviews of them. They probably sound better than most so called "pro audio" hobby musician interfaces in the same price range.
Moving up to true professional quality you have Lynx E22 (600,) or anything from RME ($$$ - german - the best.) Lynx is good build quality, good sound quality, but probably not as good as an audiophile bred DAC and not a good value unless you need the pro audio features like signal routing, hardware dsp, ultra reliability, etc.
The PCI format is less popular now, USB is taking over. Make sure your old PC can handle the PCI formats used in the new cards.
If your old PC has USB 2.0 ports, you're probably better off choosing a $400-600 USB DAC since that is the rage now and there are a million of them with modern DAC chips and low jitter clocks. This would be the best resale value too. If you buy it used then it's "free disposal" when you're done.
I think you would get similar or better sound quality as the PCI cards or $500 commercial USB DAC by using a Raspberry Pi 3 (RPi3) and
HifiBerry DAC+ Pro. Low jitter, nice DAC chip, simple output stage for $100, includes the server (RPi,) the DAC (Hifiberry) and free linux audio OS and software player (Rune, Volumio, Raspbian, etc.)
The only reason to need the processing power of a PC for audio playback nowadays is if you want to do convolution dsp like low frequency FIR crossover, EQ and room correction. But to just spin the tunes from web or local files, you just need a little Raspberry Pi.
The nice thing about the HifiBerry audio accessories for RPi is it is all extremely minimalistic, so the price is kept down and simple to assemble and use. There are also other brands of RPi DACs and such.
If I get my DAC mods working I'm getting a RPi for silent USB source.