Higher Impedance MC Carts on Transimpedance Stages?

Nothing blows up. The mating would be inefficient as the internal impedance of the cartridge exceeds the input impedance of the BMC, which we think is around 2-3 ohms. Thus some of the signal voltage derived in the Kiseki would be lost to ground.  But also, the Kiseki probably produces very little signal current; you can estimate that by dividing its output voltage by it internal impedance.  I don't know the output of a Kiseki but for example if it is 0.4mV then its signal current is around 0.4mV/40 ohms = ~10 micro-amperes.  For comparison, even my Ortofon MC2000 which produces only .05mV of signal voltage makes 25 micro-amperes of signal current because its internal impedance is only 2 ohms. Nevertheless, one might take advantage of the BMC's adjustable gain (0, +7, +11, or +14db) and set the gain high using the internal jumpers. My prediction is it won't be satisfying but worth trying.

Mathematically, current (I) is defined as the Voltage (V) divided by the Resistance (R):

I = V/R

The current (I) is inversely proportional to the resistance (R) , i.e., the higher the current, the lower the resistance and vice versa, the lower the current, the higher the resistance.  Therefore if the resistance of your cartridge is high, you will get lower current and as a result also lower voltage.  High impedance cartridges will result in lower output and will sound like your phonostage doesn’t have adequate gain.

I worked this out. Bandwidth is where current is half of maximum. This occurs when impedance from cart inductance equals cart resistance. If the bandwidth is acceptable, cart will run fine.  Bandwidth is given as:

f = R/(6.3*L);

Or you can use the handy calculator I placed on this web page:

https://www.hagtech.com/loading.html