Tfkaudio,
Blackbird HO MC is rated at 2.5mv output so you don't have to restrict its use with only MM phono stage's 47kohm. Since the Blackbird is a MC cartridge (at 2.5mv) I believe you can match with any MC phono stage to get more flexibility in terms of gain and loading settings. 54db gain and 500ohm loading are only a starting point. You can increase or decrease the gain but keep the loading below 500ohm for better sound in my opinion.
Blackbird HO MC is rated at 2.5mv output so you don't have to restrict its use with only MM phono stage's 47kohm. Since the Blackbird is a MC cartridge (at 2.5mv) I believe you can match with any MC phono stage to get more flexibility in terms of gain and loading settings. 54db gain and 500ohm loading are only a starting point. You can increase or decrease the gain but keep the loading below 500ohm for better sound in my opinion.