Subwoofer boom is too much for me...

Either you've got the wrong sub-woofer, else it's in the wrong place in your room or you've got it turned up too high.

Sorry for so many options, but I've got all the basses (ho ho) covered.

This has worked for me every time I’ve set up a sub, whether it be REL or another brand. The idea of keeping the crossover as low as possible while volume high was tough to swallow at first, but now makes sense.

A horrible compromise at best and only recommended if you can do nothing about the response of your mains. Meaning, no high pass filter and won’t/can’t plug your port.

Many A'goners have gone the other way and been much happier.

Spend $10k on dsp, bass traps, diffusers, and absorption. Or, get a pair of athletic socks, ball them up and stuff them in and send me the $10k.

Also think placement then crossover setting/gain key. Perpahs four is too many?

Much has to do with the quality of your sub , I went from the $500 Svs pro 

to the 1000sb $1000, to the $svs 4000 sb $1800

and the 1000 had much more control and articulation ,

then to the 4000 SB-Sealed box. It took it to another level altogether the bass much faster,more articulate and controlled. ,No boom whatso ever .

you didnot mention what subwoofer you were having issues with.