To answer one of your questions as it concerns the source of your music. Always start at the source of the sound, you cannot fix detail and life in the sound that which is not there to start with.
I would recomend your money would be well spent first on a Shure V15. Any DJ cartridge is a joke compared to this quality of cartridge, bass punch, detail and top end distortion are a fraction of any DJ model. I often listen to vintage MK3 from the seventies (getting very pricy and rare NOS on ebay) but many use the latest models for what you want to do. Did I say a night and day difference plus like buying a new pair of ears!
Whilst purchasing Shure a stylus weight pressure gauge and alignment card is useful.
Feel free to investagate isolation methods discussed in other threads, they are relatively cheap first steps towards improvements.
I personally found my Rega based arm to be a waste of time, do like SME 3009 combined with forementioned cartridge for Hi Fi but may not be suitable for high SPL enviroments. Ask GSA on that one!
The above steps will really show up bad production.....sorry!