I would suggest that you stick with the 5 speakers you have. You seem to like the sound, and if you add two more speakers there is a high probability that your receiver will not have enough total power to drive all seven.
That receiver has a 100 watt per channel rating for 2 channels, but its power supply is only about 350 to 400 watts or so total. That is not enough for seven channels, despite the manufacturer's misleading specifications. They lie.
That means it can drive 5 channels to 70 or 80 watts each, maybe, but with all seven channels driven it will be lucky to put out 45 watts per channel; some will only do 35 or 40 watts per channel, which is completely inadequate.
If you really want to go to 7 channels, you will need to get a 100 watt per channel or larger stereo power amplifier to drive the front two channels, and then the receiver will have enough power to drive the remaining 5 channels.
Your speaker power ratings you quoted there are the MAXIMUM power that you can drive them with without overheating the voice coils and damaging them. You don't have to worry about overdriving them with your receiver; it doesn't have enough power.
A minimum for a subwoofer IMO would be one with a 350 watt RMS amplifier and a 12-inch driver.
You will probably not get an adequate one for under $300, so shop around and see what is available.
The Polk Audio PSW505 is one that might be OK; Amazon has it for $290 right now.
Originally Posted by Clueless1609
My family is finally upgrading our basement home theater. We’re replacing our 15 year old rear projection TV, and receiver. We’ve gotten a new Benq W6000 projector , Panasonic Blu Ray player, and a Yamaha RX-V571BL 7.1 AV Receiver. I was planning to keep my old 5.1 speakers because they sound pretty good. But, I went to hook up my old speakers and found that my subwoofer won’t work. It has speaker wire and the receiver wants a mono pin. So it looks like I need a new subwoofer. Or is there an adaptor? Also, since the new Yamaha is 7.1, I was thinking I might add the two extra speakers. But I don’t know what subwoofer I should get, and what side speakers I should get. Or should I move the back speakers to middle and get new back ones. Or should I toss all the speakers (gulp) and get all new ones. If I just add on then I’m not sure what size or brand or does it matter? Help, please.
My 15 year old speakers are:
Front two: Technics SB-LX70 200W (music) 100W (DIN)
Back two: Technics SB-AFC32A 260W (music) 130 W (DIN)
Subwoofer: Technics SB-W33 200W (music) 100W (DIN)
Center speaker: Cambridge Soundworks Center Channel II or Plus (don’t know wattage but it is 25” wide by 4 ½ “ high)
Thanks so much for your help!