If you're into lo-fi black metal then I think a good place to start is shit like the early Sacred Bones Records releases. They used to put out a bunch of really good left-field post-punk stuff and experimental stuff. The new stuff is really fucking killer but certainly much more refined and different. Night People also has a slew of cool bands that you'd like a lot if that fractured sound is what's up with you. You mentioned Interpol so I'd throw out Blank Dogs and Crystal Stilts. For Joy Division, I'd recommend you go to the classic post-punk bands of that era. The Fall, This Heat, Gang of Four, The Cultural Decay, 13th Charm - all those guys would be up your ally. Also, read "Rip It Up and Start Again: Post Punk 1978-1984" by Simon Reynolds for a kaleidoscopic view of the entire movement during its pinnacle. For Sonic Youth, go right to all the No Wave bands. DNA, Teenage Jesus & the Jerks, Swans, The Contortions are where it's at in regards to bands that are similar to Sonic Youth.