Can you run the HANA SL MC at 100 ohms?

Chili, I think you are underestimating the technical expertise of the designer at DB Systems.  The kits are meant to be used in conjunction with a phono stage that has a fixed input resistance of 47K ohms.  For other fixed input resistances, I suppose they can provide custom values, but as you intimate, the final net resistance of two or more resistors in parallel can never be higher than that of the lowest value resistor in the parallel grouping.  Most audiophiles know this, let alone all EEs.  I don't think it's "widely believed" that resistances in parallel are additive.

By the way, SUTs cannot have a "fixed" input impedance.  Transformers do not per se have an impedance.  The device on the primary side sees an impedance equal to that of the device on the secondary side divided by the turns ratio of the transformer.  I guess you know all this, but your post makes me wonder what load you are presenting to your Hana.  For the Hana to "see" a load of 100 ohms, using a SUT with a 1:10 turns ratio, the resistance on the secondary side must be 10,000 ohms.  Is that the case?  If the turns ratio is other than 1:10, then take the square of that turns ratio and multiply it by 100 ohms to find the value of the resistor on the secondary side, at the input of the phono stage, which would give a 100-ohm load to the Hana.
On paper, 100 ohms should not be optimal for the Hana SL, with its internal resistance of 30 ohms, but you like what you like.

>I think you are underestimating the technical expertise of the designer at DB Systems.
>The kits are meant to be used in >conjunction with a phono stage that has a
>fixed input resistance of >47K ohms.

Then I wonder why @andysf suggested them as a remedy in response to the original post which asks:

>My own phono stage only allows 100 ohms
>for MC cartridges-as do many others.
>Has anyone tried the Hana at 100 ohms and were you
>happy with the result?

@andysf said:

>I have a Hana EL which is basically the same thing specwise.
>I bought this from dB Systems...etc...

Surely, neither you nor @andysf propose plugging a Hana SL into a normal 47kohm MM phono input and adding loading plugs. I tried my Hana SL direct, that is, without a SUT, one time and the sound was thin and lacked dynamics. I could hardly wait to remove it!

>For the Hana to "see" a load of 100 ohms, using a
>SUT with a 1:10 turns ratio, the resistance
>on the secondary side must be 10,000
>ohms. Is that the case?

No. My Rothwell MCL SUT is resistor loaded. https://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/8r0AAOSwYXVYya~I/$_57.JPG?set_id=8800005007

Seriously, think no more, pull the trigger! I’ve had mine for nearly a year and for the first time since I got my Shure V15 Type IV with the Jico SAS neo stylus, I haven’t looked back. It’s amazing, even cruddy ‘70s pop rock recordings are tolerable, a really disruptive cartridge, best I’ve ever owned!

PS: Mine sounds sublime through my Gold Note PH-10/PSU-10 with the loading set at 220 ohms

Don’t want to hijack the OP’s post but I have a related question for you impressively knowledgeable fellows.  I know very little about how this all works: I simply enjoy the warm and liquid sound of records.  Anyway, I’m told that the moving-coil input impedance of my 834p has been measured to be 515 Ohms.  Is this maybe why my experiment with the Hana SL hasn’t moved me to the levels of enthusiasm expressed here and by so many others?   It does sound very good to me, with lots of detail, but it’s not really any more emotionally stirring in the mid-range to me than my last couple of two-or-three-hundred dollar cartridges.