Subwoofer boom is too much for me...

Try it. 
I’ve done it with different results but IME a properly built sub (ported) should not have a stark difference than a properly built sealed one.

Might try the gain first, and the crossover settings and slopes may have more immediate effect than plugging the port

Placement.

Placement and EQ are your best friends, followed by a good corner bass trap.

Use the AM Acoustics room mode simulator and try to keep your listening location and sub out of the lowest room modes if you can.

An EQ and/or bass trap then is your friend.  Boomy bass is usually caused by narrow and tall peaks, which ironically, keeps you from turning up the subwoofer!

Yes, you can plug a subwoofer, but honestly good to measure if you can.  Tailored DSP/EQ for your problem can often be required.

I’ve done it with different results but IME a properly built sub (ported) should not have a stark difference than a properly built sealed one.

@johnnycamp5

The issue isn’t the quality of the sub. The issue is the amount of bass in the room with this particular sub. Sealing a port will raise the lower cut off, and this may help the OP balance the bass properly.

As I’ve written lots of times, audiophiles are conditioned to think we can glean insight into a system’s response by specs, but in truth bass response is hugely variable and specs go out the window when it comes to integrating a sub into a room.

Below ~ 60 Hz speaker specs don’t tell you a thing once they are in the room.

Agreed

I should have made it clear that only after extensive room treatment (bass traps)

I suppose I have tunnel vision that way…

I would not even consider positioning of sub or subs until after bass traps and/or treatment…

I did do it once that way though…

The room shape was atrocious as well- 15w x 28L x 7.6 high (all plaster walls also bad hard no lossy surfaces) 

only became somewhat acceptable after 4 subs…but the ringing was still generally unacceptable…