This is probably the best SPC player of them all. It has a myriad of features: speed/pitch change, channel mute, echo disable, DSP pitch/volume registers, etc.
Use the left and right arrow keys to toggle the data viewed during SPC playback.
v2.18.4 (build 7379) (2021/07/31)
This updated version of spcplay fixes a bug which causes some sounds that do not output because of catching up of KOFF immediately after KON is too fast (i.e., happens with the Asterix and Obelix soundtrack). As a bonus, it also adds more play speeds and volume levels in the Settings menu.
At first when I tried using this in WINE, I got error 306. According to their error code page, this is a driver issue. And the WINE error, which I observed by starting this from the terminal, was apparently error 0x80004005. The sound issue was fixed for me by installing the packages lib32-alsa-plugins, lib32-libpulse, and lib32-openal using pacman (I use an Arch-based distro). If you install the equivalent packages for your distro, hopefully it'll work for you as well. I'm writing this so it's more convenient for others to use this software in the future on Linux with WINE.