From a CNET article. Try both.

"One of the other controls you may find on your subwoofer's rear panel is marked "phase." It's provided because the speakers and subwoofer sound best when they are in-phase -- meaning their woofers move in and out in sync with each other. To check your sub's phase, play music with lots of bass, listen for a minute or so, and have a friend sitting by the sub flip the sub's 0/180-degree phase switch slowly back and forth. The correct setting is the one that yields more bass. You may have to try a few different recordings before you hear any difference, and it might help to turn up the sub's volume level for this test. If you don't hear any difference between the 0 and 180-degree settings, leave the phase control in the 0 position."

Phase is this... When a bass note hits the woofer will move outward. When phased at 180, when the bass note hits the woofer will move inward. I personally like mine phased at 180.

By itself, meaning only the sub is playing, is irrelevant to the listener. However, when playing along with the midrange and tweeter speakers it matters because when “in phase” the speakers are all either pushing out or pulling in at the same time. When out of phase, certain frequencies or sound will be cancelled. In other words, One is pushing when the other is pulling. Therefore, switching between 0 and 180 is the same as reversing the wires to the speaker. Normally, you’ll set it to 0 if all the speakers are wired correctly. However, if the sub is pointed such that the bass reflects off a wall before it gets to you ear and the other speakers are pointed directly at you, then you may want to switch to 180. You will hear a difference. The midrange sounds will typically be at a lower volume. Throw the phase switch and see if the volume seems louder. I tried to keep the answer as non-technical as possible. GL.

Most times 0 is appropriate. As others have said... typically the 180 is necessary only in large rooms or when the sub has to be placed very far away. I’ve setup maybe 4-5 different home theaters and at least 3-4 subs for pins in my arcade and never needed 180. But your experience may be different.

This^^

If you have multiple woofers (i.e. the one in the pinball cabinet and the external Polk), then you would want the woofer cones to move in unison. Meaning both moving in the same direction, which reinforces the bass. Out of phase tends to diminish the bass since the cones are moving in opposite directions.

So to answer you original question...the 0/180 switch 'reverses' the direction of the external sub. By providing the switch, you have an option to get the external sub moving in the same direction as the internal pin sub.

Its essentially to make sure in a home theater setup that the sub is in sync with your other speakers. Almost all the time its going to be set to 0.

I woudnt go over 120 hz. You get a lot of good mid bass from 60-100or so. Anything much over that is gonna make it sound blah. Mine are all around 100 or less.

My PSW10 is loud enough that any setting is fine on that adjustment. I have it on about 1/2 volume and you can feel the vibrations. My wife says that she is not sure if the shaker motor or the subwoofer vibrates the machine the most. It makes a big difference in the sound and music from the machine. If I put it any louder than half volume, it disturbs my teenagers on other side of the house with the doors to their rooms closed. They tell me that they have trouble hearing their video games and concentrating. I just giggle a little bit...

I use the pinnovator output and input those through the line level input. I split those with a pair of rca splitter and run 2 games off each sub. Works perfect. https://www.amazon.com/Cable-Matters-5-Pack-Plated-Adapter/dp/B0141KPCDY/ref=mp_s_a_1_12

But yea, you want your wires on the input. I’m actually surprised it worked the other way? Never tried it myself... what would be bad tho is having something going into both input and output I’d imagine.

The way those are set up is so that in a normal audio system the speaker output from the amp/receiver goes to the "input" connections on the sub. The crossover on the sub then separates the frequencies. Everything below the crossover setting is produced by the sub. Everything above the crossover setting is sent to the "output" connections of the sub, which then go to the the regular speakers.
Connecting a game to the output speaker connections of the sub really should not work. Connecting to the input speaker connections should have the sub produce the frequencies below the crossover level.

Yea it seems odd. Also, I thought the only way to bypass the crossover is by using the lpf. That said, lpf produces better bass n such for movies, but using the crossover on the sub typically sounds better for music.

I switched mine to try how yours is set and it was horrible. Check all your connections, maybe you're grounded on cabinet speaker. should be noticable diff

Why do you have 4 connections? I have mine wired to the subwoofer in the cabinet. Two wires, positive and negative, and then into the subwoofer input, right side, positive and negative.

Anyways, I like to play with the low pass filter and I feel it needs to be set differently for each game. I start at the highest and work my way down. The speakers in the machines arent getting to low levels, so it really depends on how many bass notes you want to hear from your game.

Two machines hooked up

Oh gotcha... When I first was reading about doing that, I was told to never do that as it could damage the machines. Not sure why exactly that would be and doesnt really make sense to me from what I know about home theater stuff.. But most of the time im not wiring line level to the sub..