I focus on the compositional aspects of the program, but I do like to be able to audition what I am making! I can use software and hardware synthesizers to do this, but it sounds like you want something with more fundamental building blocks. OpusModus is able to integrate with Common Lisp Music (CLM) https://ccrma.stanford.edu/software/snd/snd/clm.html. Info on integration with OpusModus here: https://opusmodus.com/forums/tutorials/clm-examples/clm-inst... CLM will give you osciallators, generators, filters and more. I am not a CLM expert, but it seems to address some of what you are looking for.

Yeh that seems to be what I'm looking for, will look into this more, cheers!