This phono uses built in MC step ups transformers. MC step up transformers present a complex load to the cartridge which is not just a simple OHM value but consists also of inductance and capacitance. I always recommend to use the phono without additional loading.
But id needed or if you want rot experiment the load can be lowered by use of the load jacks on the back.
The phono can be configured for low output impedance carts(less than 10 Ohm) or for medium output impedance carts up to 25 Ohms.
This is configured when I assemble the phono but can be easily changed afterwards by any qualified technician.
If required I can do this with a switch to make it user configurable but to get best performance I do not recommend this. The low impedance and low level phono signals are where you do not want to have switches.
I see this topic being raised often but I can assure you that the range of carts is not that limited as many people think. I have customers who use the phono which is configured for low impedance carts even with medium impedance ones and report good results. Only high impedance carts and extremely low level carts are not recommended.
With phono and cart matching it is just as critical as with speaker/amp matching. If you want an amplifier to work with a huge range of speakers you need a very high powered one. But that is sonically not a good solution for very sensitive horn speakers. And vice versa if you want a speaker to be able to work with every amplifie you need to pick a very sensitive one. but then it will probably not be listenable with SS amp.
I choose to go for best sound quality and therefore compromise flexibility a bit as the other way round