Does you Prima CD player have a digital output? If so, you may want to consider a used Prima DAC, which has the Capitole Mk,II d/a converter in it. It is a big step, and a logical one for your situation. There are a couple available on Audiogon right now.
Then, if you're not quite "there" yet, you will know that it is not your source that is a limtiing factor, and you should look at improving your amp....