What would it be the difference between :
-Nigdy nie słuchałem tej muzyki
-Nigdy nie posłuchałem tej muzyki
I thought the first could be a recurrent action in the past, therefore the person has never listened to the music, in a way that he has never got used to do this task. The second sentence would mean that he has never listened to it. Well, i`m a bit confused, i don't know if you understood X)
In English, there are no perfective/imperfective verbs, so the aspect of the verb is determined by context. Posłuchać just reduces the listening in general of the music to a specific occurrence of listening to the music. Since it's determined by context in English, the translation is the same in this case.
"Nigdy nie słuchałem tej muzyki" means that I'd never play it to myself (although it's not like it's impossible that I ever heard this type of music).
"Nigdy nie posłuchałem" rather doesn't make sense. "posłuchać" is like 'to listen for a bit'. "Posłucham muzyki" means that I will listen to the music for some time.
There's also the real perfective "przesłuchać", but it makes sense with something... complete. Like a song, or an album, but not 'this music'.
So let's say "Nigdy nie przesłuchałem tego albumu" suggests that I was supposed to listen to this album (this 'supposed to' part is something present in similar verbs: to watch, to listen to, to read) but I never did. "Nigdy nie słuchałem tego albumu", despite the imperfective part, is a simple "No, I never listened to it".