There's a lot of good advice here. I'll add my 2 cents from personal experience regarding the cartridge. If you choose the RP-3, upgrade the Rega Elys cart since it has a lot of detail in the highs and can sound sibilant in some systems. You don't need extended highs when playing punk.
I also agree to eventually add a subwoofer. Music will then sound much more balanced in your room.
I also agree to eventually add a subwoofer. Music will then sound much more balanced in your room.