They're both right, bass is bass no matter what you do it'll travel. A less thunderous sub won't shake the room as much as a big sub.
However the rel t has tiny driver, barely better than your speakers in low frequency ability, and expensive.
If you just want a cheap but decent build sub look at bk subs. There's the Gemini, double Gemini, xls 200 and xls400. Monolith and monolith plus
Yeah see what you mean both statements are correct but both counteract each answer to the question - which one is going to be noticeably bassy but less neighboury.
The answer I was expecting was something like "the lower the sound frequency, the more likely it is to travel through walls".
I am purely guessing if a 6" sub or a 12" sub produce the same frequency, then it makes no difference the size of the sub:they both produce the same frequency/sound wave???
However the 10" sub I would expect to go lower, when called upon, and therefore LIKELY to be more neighboury. Would anyone agree?