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.
v2.18.3 (build 7258) (2021/03/14)
This updated version of spcplay fixes a bug that stops playing when some strong FIR filters are applied.