How old is the Bronze cartridge? How does the stylus look? Is it worn out? Before getting a step up Tranny you should look into those questions. If the stylus is worn then you can get a new one if the cartridge is not too old. If not, why not look for a good MM or MI (moving iron)cartridge. This may be the ticket to better sound.
As to the phono preamp, It is as important as the TT & arm and should not be overlooked. I don't know how good the one in the Nova is but I suspect it is the weak spot of the vinyl system. I do NOT like step up trannies unless absolutely necessary. Others will disagree. I'd put my $$$ into a good phono preamp first rather than tranny. But again, the stylus may be the problem. Get a jewelers loupe or USB microscope and look at it .
As to the phono preamp, It is as important as the TT & arm and should not be overlooked. I don't know how good the one in the Nova is but I suspect it is the weak spot of the vinyl system. I do NOT like step up trannies unless absolutely necessary. Others will disagree. I'd put my $$$ into a good phono preamp first rather than tranny. But again, the stylus may be the problem. Get a jewelers loupe or USB microscope and look at it .