Looking for a suggestion for a good Phono Stage

It appears upon further research that I am running the phono through a phono input. Other than upgrading to a Grado Prestige Gold, any other tweaks or equipment recommended to improve my over all sound? I think my complaints right now is that compared to my CDs my record sound is a little flat. The bass seems to lack punch, and the highs could be smoother.

Mechans- I think the cartridge is a Grado Green Prestige. I would probably upgrade the cartridge at some point. I don't believe the particular ARC SP4 I have has a built in phono stage. I believe ARC put out an SP4-A that had the phono stage. I don't want to spend much more than $200, either new or used. I do have a fair collection of vinyl, but most of my investment is CD.

My SP-4 has SPARE, TUNER, MAG 1, MAG 2, HEAD AMP input selection. I run my phono through MAG 1. Am I getting that part right? There is a fair amount of hum coming out of the speakers until I begin to play a record. I have decided to upgrade to a Grado Prestige Gold (from the green) unless somebody has an idea of a comparably priced cartridge with better synergy. What about Pro-Ject Tube Box for the stage. A little up in price from the $200 I quoted, but maybe worth it? I apologize about my lack of knowledge in this field. I did not grow up around vinyl and decided to do a 180 degree from setting up my system to play PC audio so I'm jumping into this head first.