A couple of years ago I asked the same question . I had the CP-35 pre-amp and I wanted to upgrade to the 47.5. The salesman told me that the difference would not be worth the money and suggested to go to a tube pre-amp. I have not looked back. I now own a Audio Research Reference 1 pre-amp. Then two years after that I bought a Audio Research VT 100 II. I have found that tube equipment makes the difference for me.
Kevin
Kevin