You might want to look into modifying your RB250. Origin Live modifications to the arm make this piece a category killer that will improve sound defination, character, etc... . There are good sights on the internet where you can read about this. Also look into rewiring for the arm with something like Cardas. Check it out.
Should I purchase an expensive phono preamp
I have a Nottingham Horizon TT with the Rega 250 arm and a Goldring 1000 series MM cartridge. This is hooked up to a Pioneer Elite VSX-99 AV receiver that has a built in phono stage. I am trying to improve on the phono stage but I am wondering if there will be diminishing returns going to the more expensive stages. I am considering Lehmann BC, Graham Slee Era Gold V and AcousTech PH-1. I listen to Jazz, Old School R&B and Classic Rock music mainly.