Maybe this is like the Sony SA-WX700 "push-pull" sub? I think they're no longer made. They were inexpensive, and I bought one. Mine broke (as did many of them, I gather) after a year or so. I still have it sitting in a corner of my listening room, waiting for me to replace a condenser, in hopes that would bring it to life. I was pleased with it, while it worked, but I couldn't give you a good critique.
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Greg
VP180, M80s, M22s, QS8(4), CSW S305s, EP500, Pioneer SC-1522
M2i, M3(2), Pio vsx-1017