thanks Chip...that's better than what I came up with.
You can find them on the "Bay" also but yeah everything throws up car "stuff!"
Something like this may be easier to hook up and adjust. You may want to build a frame or stand for it rather than cutting a hole into the subwoofer cabinet. Search for "subwoofer plate amp". Lots of choices between 25 and 1000 watts depending on budget.
https://www.amazon.com/Dayton-Audio...8-6&keywords=subwoofer+amplifier+home+theater
I don't think he is talking about ... adding a "Plate Amp" into the sub he has???
If the sub he has is truly from a HT in a Box ... then really it's not worth the trouble??? It turns out I have one of those?? Small ported sub, I think?? And it only has two speaker leads coming from it???
I'm using some small "Concord" speakers ... that I just knew had to suck?? But I found I like them!! But they don't have any bass to speak of??
I'm using a Sony HTR and apparently that Receiver, the five tiny speakers and that Sub are all from
the same HT in a Box??? I only realized that when I went, to hook up a "real sub" and found only spring clips for a sub hook up, on the back of the HTR, WTH???
Most likely it's something I got for free from neighbor?? It's actually not a bad little HTR??? It has only became a problem when I went to hook the sub!
It's in the bed room so lite duty anyway and using, my surprisingly listenable Concord speakers! And the Concords only became a "lack of bottom end" issue because the "living room system has bottom end ... and the bed room system does not! It was fun for awhile but the lack of "Bass" is getting old.
Oh well ... back on point, It sounds like you can use either a new amp or a powered sub??? And just going by what we know and perhaps I missed it but if your sub can't be hooked up to your Yamaha , I don't think it's really worth bothering with?? If it does not have or low level inputs???
It really does not seem worth the effort of bothering with, but I don't know?? But as has been mentioned ... "Plan B" would be a "New" Powered Sub! Lot's of options and one for every budget these days!
Either of these would be a good choice for a small sub, they came up in another thread.
https://www.monoprice.com/product?p_id=8248
https://www.parts-express.com/dayton-audio-sub-800-8-80-watt-powered-subwoofer--300-627
And if you decide you want more sub down the room ... you'd have a great base for another "Smaller system!" A "Plan B" if you will.