Here's the manual for the A3CR:
http://www.musicalfidelity.com/uploads/manuals/English/a3crpre_eng.pdf
The A3CR has an MC/MM switch on the back. Turn the volume all the way down before toggling the button.
They list the sensitivity of the MM section as 2.5 mV, which is on the low side (lower sensitivity => higher gain). That sensitivity seems more optimal for the high-output MC cartridges which are typically in that range. The output of the Ortofon is 5.5 mV.
As for the warmth issue, it could be a less than optimal match with the A3CR, but it could also just be the sound of that cartridge. I'd suggest exploring some of the more affordable MC carts. Note that you'd still use the MM setting for high-output MCs.
http://www.musicalfidelity.com/uploads/manuals/English/a3crpre_eng.pdf
The A3CR has an MC/MM switch on the back. Turn the volume all the way down before toggling the button.
They list the sensitivity of the MM section as 2.5 mV, which is on the low side (lower sensitivity => higher gain). That sensitivity seems more optimal for the high-output MC cartridges which are typically in that range. The output of the Ortofon is 5.5 mV.
As for the warmth issue, it could be a less than optimal match with the A3CR, but it could also just be the sound of that cartridge. I'd suggest exploring some of the more affordable MC carts. Note that you'd still use the MM setting for high-output MCs.