Alternate Sub Hookup
I recently purchased a full HT setup at a yard sale for $100. It included two Monitor 70's, CS20, 2 Bose 301 series V, and a PSW202 along with a Yamaha RX-V371. Unfortunately the PSW202 is not working. I have a sony DAV-FX500 system I used to use. I had the idea of using this along with the subwoofer that came with it. I don't want to spend anymore money right now on it. Could I use the subwoofer out on my yamaha to feed the DAV-FX500 with the line input to utilize the subwoofer?
The DAV sub is a bass reflex type. It needs to be powered from an external source. Sorry, you can't use it with your AVR. That speaker is 3 ohm, which is too low of impedance for your AVR to safely run. I understand you really don't want to put a lot of money into this system, but I would look at a low end powered sub, and get rid of all those Sony speakers. You really can't use them on very much equipment, other than other HTIB systems.
Look at some inexpensive subs, you'll be surprised at the difference that you will hear in compared to what you have been hearing. Energy has some fairly good entry level subs.