Catridge Suggestion for Audio Research PH-5

Ortofon jubilee has worked nicely for me for several years.

I think your cartridge is the better of the 2 pieces. If it was my system I would keep it. You can get a head amp to get the gain up to where you need it or you can just replace your PH-5. I wouldn't be so fast to give up the benefits you get with a low output cart.

Can you suggest some head amps which go well with my system.

Have you considered getting a step-up transformer?

No. I did not. I am new to this and have no experience with stepups. Will there be a quality difference with stepups ?