The Hyperion Mk2 has an internal resistance of "10-11 ohms" to quote from Soundsmith directly. Thus if it was an MC cartridge, you might expect it could be loaded with 100 ohms or higher. The recommended 470 ohm load (or higher) not only suggests a SUT with a 1:10 step up ratio but also tells you that because of its inductance, loads below 470 ohms might result in loss of gain and in some cases treble rolloff. The Hyperion has a stated coil inductance of 2.75mH (milliHenries). Whereas a typical LOMC cartridge with a 10-ohm internal resistance would have an inductance of around 10 uH (micro-Henries), or less. The inductance of the Hyperion would add 172 ohms of reactance at 10kHz, for example. Which is why you don't want to load it down too much.
