I'm using Paradigm Studio 60's in my HT. They're not bad. I wouldn't necessarily use them in an audio system but I don't think the Paradigm's will hinder your enjoyment of music. I have heard some of the newer Monster Cable IC's that you can pick up at any Best Buy or Circuit City. They should be good enough to let you hear what's going on. If it were me I wouldn't get to crazy unless you really start upgrading equipment.
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.