[dimatura]

I've never actually used sox for fx, I wonder how good they are. (I have used it plenty for resampling, normalization, trimming, etc). But regardless, there's thousands of VSTs out there -- a lot more options than whatever sox has built in.

[jcelerier]

IIRC Sox can apply plugins, maybe not vst but lv2 or ladspa

[xorcist]

sox filters are generally high quality, they weren't designed to run in real time.