Worth stepping up to a preamp?

Do you mean a phono preamp and keep the receiver? There are some nice $200 phono preamps to be found used on the Gon. If your Sony is surround sound, then you have to make sure it doesn't digitize analogue inputs. If it's an older stereo receiver it probably doesn't. Other posters might have some suggestions for a cartridge upgrade that would do more. Good luck

You know, I tried to do some research so that I wouldn't sound terribly naive. D'oh. I guess I'm not sure (preamp+receiver). The receiver is surround 7 ch. and no more than 2 model years old.

Your receiver is pretty new. You might want to invest in new speakers (or new/used ones from the gon). FYI there are sort of two "kinds" of preamps--control centers and phono preamps. Sometimes (all the times before cd's) a control center preamp will include a phono preamp. Nowadays, the control preamps mostly are "line level" without a phono preamp. YOu can think of your Sony as (among other things) a preamp + a phono preamp + power amplifiers. So it's all in one. You COULD run your turntable through an external phono preamp (one you'd have to buy) and then run that into a non-phono input in your Sony (like a vcr or dvd or whatever). But at this point, speakers makes the most sense to me. Good luck!