An introduction to computer audio
A couple of aspects to consider are:
Streaming audio players in general don't have moving parts; they are quiet by design.
It is possible to buy or build a PC with few or no moving parts.
In case of classical music, check if it is possible to browse by composer.
MP3 support is almost universal. If you want CD quality, check which lossless formats are supported. WAV is a popular lossless format but support for tagging WAV is poor.
Supported bit depth and sample rates.
CD quality (16 bits/44.1 kHz) is standard. Check if 24 bit depth and higher sample rates are supported if you plan to play high resolution audio (88.2 – 192 kHz).
Check if gapless playback is supported. Nothing as annoying as having some white space in a life recording or between two movements played as one.
Note that gapless playback is not a part of the DLNA standard.
In case of streaming audio players, you need a home network as the music comes from the internet or from another computer (often a NAS) in your network.
Hard disk players can be used without a network but often they use online databases to lookup Meta information (tags).