What is the norm? How many of you use the subsonic filter with your turntable?

Both my pre-amp and power-amp have subsonic filters. Have played around with them. Both are turned off, and never really needed. I understand if you get rumble, the filters are necessary. 

Interesting about the sealed box theory. Both my speakers and subs are sealed, my TT is isolated on a platform with rubber footers. I can jump up and down next to it with no issues. 

Wonder how much rumble is an issue with the level of turntable, meaning, the lower quality tables might be more prone to rumble over the higher quality ones? Or maybe phon-preamps are just better now, or carts are better?

Actually, I forgot to ask this also... for those that do not use a subsonic filter... are you using that weight that sits on top of a vinyl while it plays to keep it pressed down? 

@dman777 I use both a 750 gr record weight and a 1500 gr peripheral ring, but even if I don't use them at all I still don't need a low cut filter. 

First, if you carefully match your cartridge's mass and compliance to that of your tonearm you should be able to achieve an optimum vertical and horizontal resonance of between 8 and 12Hz. This is precisely what you do to ameliorate the effects of record warp information being amplified and sent to your speakers.

@dman777 @faustuss ^^ This!!

My preamp has bandwidth to 4Hz. I've no problem with excess woofer excursion at all.

I use Sota's Reflex record clamp.   It's a nice accessory