The simplest you can do for that TT is to change the RCA jacks. To significantly improve the sound without having to do readjustments down the line would mean:
1) cooking the whole wiring patch (headshell, tonearm, ICs). If you have a computer tower you can spare you can download the generator program from Marchand Electronics.
2) addressing the speed sensing/correction isue of your table. Your TT's mechanism has to fight line noise and keep the platter turning. Line filtration will help. If you can use a cheaper cryo'ed cord things will get better.
Is the TT worth going through all this trouble? That's not the real issue. You will learn a lot and will be able to reach your own conclusions. Next time someone parrots away one of those flimsy glass and particle board TTs you'll know better...