Need advice on a good Phono preamp

I currently have a Music hall 5 with upgraded kimber wires .
It has a new Benz Micro Gold Low output moving coil cartridge.

I have currently a low cost opera audio PPM-6 Phono preamp.
I get a low hum in the speakers and it does not seem to do the job.

I can sell it for a loss to move it and can invest up to 700.00 US for a used phono that works well with a low output MC .5MV....

Or should I just sell the cartrige and buy another MM or High output MC???

I used a PS audio PCA2 preamp and a Halo A-21 Parasound paired with Revel Preforma 30's. I listen to rock and jazz.

I use good Nordost and cardas cables.

Thanks in advance for any info......

Ben