I hat to say it, but if you can't crank the volume and bass very much I wouldn't upgrade anything yet. Set aside an upgrade fund so you have a few $$ when you move to a house or townhouse and you know how big a room you are dealing with.
I just received a copy of "Jeff Wayne's War of the Worlds" album on SACD in the mail today (ordered a few days ago from Amazon). Haven't had a chance to listen to it yet but I have very high expectations.
I had the tune for "Forever Autumn" floating through my head for a couple of years until I gradually remembered enough of the lyrics to figure out the title, Google it and find the album. I never owned the LP or I might have saved a couple of years