The Rega tonearm's lack of VTA adjustment is a serious problem when using cartridges other than Rega's own. It takes me a week or two of listening and several iterations to get VTA right. VTA is *crucial* for getting good sound and low noise. It's not impossible to set VTA optimally with a Rega arm, but it takes a hell of a lot of work and commitment to change those washers in and out. If I owned a Rega arm, I'd buy an after-market VTA adjuster.
As you've identified, an MC's low output demands a higher-quality phono stage. A Phono Box is not up to it. I heard a rumour (from UHF magazine) that the new Rega MC phono stage is very good for not much money.
I wondered also if your Ortofon is brand new. Cartridges take 40-100 hours to break in, and some are quite compromised straight out of the box.
As you've identified, an MC's low output demands a higher-quality phono stage. A Phono Box is not up to it. I heard a rumour (from UHF magazine) that the new Rega MC phono stage is very good for not much money.
I wondered also if your Ortofon is brand new. Cartridges take 40-100 hours to break in, and some are quite compromised straight out of the box.