I have 2 Digital Design 3515's for sale. They are dual 4 ohm. I have had them only about 4 months. I only had them installed for about 2 months. I want to get rid of them because I like to be loud with as less as possible. I am honestly asking 550 for the pair. I know it's expensive but if you know DD you know why. I accept payments through paypal and I will take a money order. I really want to get rid of these so please respond to this thread. I also have a Ma Audio HK802sx amplifier. I would give specs but I am really tired and going to bed but you can look up the specs for that amp on yahoo or google.