A DAP (Digital Audio Player) can be a streaming audio player, a PC or a hard disk player (often called music server).
A couple of aspects to consider are:
Streaming audio players in general don't have moving parts, they are quit 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).
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).