For the record: this is in an audio-only system So I have been using my current system for awile and decided the woofers in my Yamaha Ns-670s weren't cutting it as they are not even 10"ers. I did some research and was stunned at the prices. I just wasn't willing to spend $300+++ dollars and WAY up on a good audio sub. So I began looking around at ebay and thrift stores. Then I was on a trip and decided to check out the goodwill. They had several subs but most were designed for home theaters (3 ohm) and my Yamaha CA-600 can only handle one pair of 4 ohm, but i have to run my NS-670s on that amp as well. Then I saw down on the lowest shelf a larger sub for $30. After a bit of looking I decided to take the chance of it not working and get it. I got it home and hooked it up and wow! Then after a close examination i realized there was no port at all. I had never seen or heard of a sub without a port. I looked up the model online and learned for the 10" model(the one i own) new they are $1600! I also noticed the brand to be " REL Acoustics" I have never heard of this company before, but am blown away by the performance. Can someone give me some more info about REL subs?