Any argument that a stepup is theoretically inferior because it adds an extra device is simplistic at best, maybe specious. An active MC stage also adds an extra device. The question is, which device works best with any particular cartridge and the following (MM) gain stage?
The answer depends on the individual components.
FWIW, the active MC phono section in my $12K Doshi Alaap outplays my $800 Bent Audio Mu (copper version) stepups, despite fanatical tuning of the Mu's impedance for individual carts. What does this prove? Maybe not much, given the price difference. Still, though I haven't heard every stepup (not even the reportedly better silver Mu) no MC section of any type has ever outplayed the Alaap's IME.
One important fact: impedance matching with stepus is orders of magnitude more critical than with an active MC stage. True afficionados may use both primary side loading (for the cart) and secondary side (Ziebel) loading (to control transformer resonance). Getting all this right in a resolving system can take alot of trial and error work. Impedance setting with an active stage, while certainly audible, tends to be less critical.
The answer depends on the individual components.
FWIW, the active MC phono section in my $12K Doshi Alaap outplays my $800 Bent Audio Mu (copper version) stepups, despite fanatical tuning of the Mu's impedance for individual carts. What does this prove? Maybe not much, given the price difference. Still, though I haven't heard every stepup (not even the reportedly better silver Mu) no MC section of any type has ever outplayed the Alaap's IME.
One important fact: impedance matching with stepus is orders of magnitude more critical than with an active MC stage. True afficionados may use both primary side loading (for the cart) and secondary side (Ziebel) loading (to control transformer resonance). Getting all this right in a resolving system can take alot of trial and error work. Impedance setting with an active stage, while certainly audible, tends to be less critical.