It is not about the walls. Low frequency is non directional. So even if you play at low volume, the neighbors can hear it unless all the walls, floor and ceiling are made of some 6" of concrete.
The subdude is nothing but a gizmo to make money. It is just a piece of MDF and packaging foam. Nothing space age about it as they claim. They are using the same deceptive marketing tactics which Bose uses to lure people into buying their junk. I have shown pictures of a DIY subdude using MDF and PC packaging foam (dark grey foam) in the subdude thread. It only costs a couple of bucks to make one.
The subdude may cut some vibration to the floor especially if you have a down firing sub but it does nothing to prevent the bass from getting transferred. If people have money to throw away, they can buy that subdude junk for some $50 and pretend that it solved all their problems
if you pay someone, they will write raving reviews about anything in a magazine. Have you ever seen any critical negative reviews of any audio/video gear in any of the magazines?
Like you said before, just use common sense and keep the volume down or use a head phone. There is no point asking here if the bass would bother your neighbors. Just play it loud and go ask them if it is bothersome. The only precaution that will be effective is not to play a sub or large speaker in an apt. at all.
If the walls of a house or apt. building can prevent the bass from getting across, you will not hear all the subs people play in their cars/trucks outside. Bass is omnidirectional and in a building made of wood, there is just no way to keep it from getting to the neighbors, even 3 apt.s away, unless you sound proof every inch of the room.
There are 100's of such threads like this where people come asking for ways to avoid bothering their neighbors in the apt. with a darn sub. There is really no way except sound proofing every inch of the room. No it is not like you have no issues. It is just that if you are lucky and get neighbors who are very tolerant to noise, then you will continue to bang your speakers/sub thinking that the neighbors cant hear them. Some may be very heavy sleepers and that would also turn out to be in your favor.
You should be glad you dont have neighbors like me
I am also glad I moved out of an apt. some 9 yrs ago when HT crap was not as popular as it is now, where a lot of people who live in apt. have a HT of some kind with a subwoofer.
I once had to sleep at my cousin's place as he was closer to the airport than I was and I didnt want to miss the flight due to snow. I could not sleep at all as the neighbors were banging their HT. He didnt care as he is a heavy sleeper and also he didnt stay in the apt. most of the time!