Is my new Cartridge Compatible?

Softone is a direct sale from Japan. Your cartridge calls for >100ohm load. Softone caps at 40ohm. I would recommend Sutherland KC Vibe Mk2 that has more flexibility. You might want to load the cartridge at 200+ to open up the top end a bit. You can do this with Vibe 2 but not with Softone. 
There are other options as well. 

Here is another option - Whest Two.2 Discrete. 
https://www.usaudiomart.com/details/650284720-whest-audio-two2-discrete-phono-stage-excellent/

You might be able to bargain it down to around $1,000. 
I use Whest Two.2 currently and really like it. To me it’s better than the KC Vibe Mk2. Lower noise, more dynamic. 

audphile1, you have no idea of what you are talking about. The Softone 4 uses MC step up transformers, not an active gain stage, to step up the output of a MC to the MM gain stage, which consists of 12AX7s buffered by mos-fets.

Since, at least, the 1970s, it has been the Japanese convention to spec the transformers at the approximate impedance of the cartridge being used. So the 40 ohm setting on a Japanese transformer does not mean it presents the cartridge with a 40 ohm load. It means that it is designed for use with a cartridge of internal impedance of 40 ohms.

Let’s do a bit of math. The 40 ohm setting of the Softone 4 coincides with a step up ratio of 1:12. Meaning, if the output of the cartridge is .3mV the step up multiplies it by 12 and outputs 3.6mV. To determine the load presented to the cartridge, we use the following formula:

Take the input that the transformer is loaded by, in this, and most instances 47,000 ohms, standard MM loading, divided by the square of the turns ratio, in this instance 12 squared or 144. And we get a reflected impedance of 326 ohms, which is what the cartridge is loaded by, not 40 ohms.

https://softone.a.la9.jp/english/Model4/M4-2.htm