Minimalist
These players are built on the assumption that minimizing the use of system resources improves the sound quality.
Most of the time this is at the expense of the user interface.
cMP² = cMP + cPlay
Price: free
cPlay is a minimalist audio player using the latest high quality SRC resampler (Best Sinc SNR 145.68db or 121.33db) or SoX (VHQ or HQ). cPlay's design offers state-of-the-art ASIO-only playback and caters for touch screen users.
cMP (cics Memory Player) is an open source audio construction. It describes how to build and configure a PC system costing around $1,000 (including a quality soundcard and case) that does not merely match but exceeds the performance of the very best CD transports.
Lots of information about this project on Audio Asylum.
Massive treats on cMP and cPlay.
JPLAY
Price: EUR 99,- single user.
Puristic design provides transcendent quality
Jplay was built with only one goal in mind: optimal music reproduction. Its stripped-down, bare-bones playback engine fits completely inside CPU cache and can be used as stand-alone player or together with popular music management software: JRiver Media Center, iTunes, Foobar, mp3toys etc.
A debate on Hydrogenaudio: Jplay - just another scam?
MQn
MQn - Just good music is an ultra-minimalist wav memory player for Windows that is stripped back as far as possible to reduce electrical and audio noise. It uses Kernel Streaming to bypass the Windows audio processing, and it works with the Windows 10 usb audio drivers or native dac drivers. Output is to USB.
Innovations are optimised render loop, page aligned memory, optimised memcpy. Each setting has been tested to ensure best sound quality, and it uses fixed time slices to align with memory page size.
Requirements are x64 Intel Haswell or later cpu with Win 10 or Win Server 2012 R2, and as much spare ram as you need to load the music you are about to play. Software versions from before 2015 will run on some older CPU's.
It plays 16 bit 44kHz wav files only, but there is a batch file that can convert flac files to wav and then run MQn.
MQN - Beginner's Guide
PlayPcmWinEn
Price: free
PlayPcmWin is yet another opensource audio player for audiophiles.
- Supports WASAPI exclusive mode playback. Bit-perfect capable.
- Memory play. Load all PCM data onto the main memory before the playback starts.
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Native C++ optimized code for the playback thread. C# .NET 4.0 WPF GUI for easy use.
- Supports WAV(16, 24, 32bit), FLAC(16, 24bit), AIFF(16, 24bit) and AIFC-sowt formats.
- DoP playback of DFF and DSF files.
- Supports CUE sheets and M3U8 playlists.
- Gapless playback.
- Source code available.
PureAsioPLayer
Price: One-time donation of a few euros for the current release.
Music desktop player with basic interface and Italian musicality.
Superb audio quality with audiophile digital-to-analog converters.
Designed for Windows 10 & 11. Highly engineered for ASIO drivers.
Has anyone tried PureAsioPlayer? - 
StealthAudioPlayer
Price: free
StealthAudioPlayer is a minimalist GUI-less ASIO/WASAPI audio player for Windows,
which supports ASIO and Vista/Win7's new audio WASAPI in exclusive mode, and with "Pro Audio" priority.
It loads the whole audio file into memory before playing.
The main feature of this player is that it does not have neither GUI nor CLI interface.
All interactions are performed by running another instance of executable with specific parameters to Stop, FF, Next etc.
I intentionally avoid using GUI for this player, anything may influence the sound.
Source: Andy
Started as a WAV/WASAPI player only, later other formats and ASIO where added.
This player has no interface at all.