Choosing an SUT?

You bring up good points about the gain achieved by the Chinook.  Other owners of this phonostage have indicated the superiority of the mm side over the mc side.  With a transformer I can exploit this advantage.   It would be great to audition candidates to see if it's true. 

When using my Herron VTPH-2A, which is also a JFET MC gain stage, I greatly prefer the sound using a SUT into the MM tube section.  I've used several carts ranging from 0.3mV - 0.5mV this way and always prefer the SUT into the Herron.  Similar results with the Chinook wouldn't surprise me.

What SUT are you using? 

I use the highly versatile Zesto Andros Allasso.  With it's range of gain and loadings it allows me great flexibility and it sounds great.

https://www.zestoaudio.com/andros-allasso-step-up-transformer-mc-to-mm-extremely-versatile/

I have not found the low impedance MI carts to be a good match with SUT's.  While the reflected resistive load can be kept in line with what peter suggests, any capacitive load also quickly comes into play and causes a LC resonance with the cartridge inductance that quickly encroaches on the top end of the audio band.

the link below has a spice simulation of a 10Ω 2.75mHy MI cart into a 1:10 loaded with 47K.  The plots show 100pf, 200pf and 300pf of capacitive load.  

http://www.intactaudio.com/forum/files/screen_shot_2020_07_09_at_61836_pm_458.png

dave