In practice it is impossible to achieve, but the practical outcome is, IMHO, the same, the lower the internal impedance of the cartridge, the greater the transfer of current to the phono stage. And that is because the internal impedance of a cartridge will likely be well above the input impedance of a transimpedance phono stage.
Agree. Jim Hagerman has posted that his Piccolo Zero’s input measures 0.02 Ohms at 1kHz, noting this value is frequency dependent. Even if its input rises a bit from that within the audible band, it should still be negligible compared to the very lowest commercially available MC coils at 1 ohm. The amount of current flow should be inversely proportional to the sum of these ohm figures (coils and input), so "Close enough to zero" is what matters for these stages. If a "transimpedance" stage had an input of (say) 2 - 4 ohm, that would be a problem.
Though I haven’t attempted to measure / quantify, the 2 ohm, 0.2mV SPU Classic GM E gets a bit more net gain from the Zero versus a 5 ohm, 0.3mV Koetsu Blue Lace (and that always felt like a "strong" 0.3mV). Both pair very nicely; the Zero amplifies these cartridges very "efficiently" and subjectively sounds GREAT with them. The SPU pairing in particular is quite special. I’ve been running both of these at 1 step down from the Zero’s max gain setting (4 total levels).
Meanwhile, a 0.38mV Colibri pairing was just not good; its coil impedance is necessarily high due to its less efficient monopole design, and though the Zero can be adjusted to give enough gain / volume (at its highest setting), the subjective result was not as good compared to SUT or JFET MC stage.
