You have to power it from the speaker outputs on your amp. You will probably need to go into the sub and out to the KEFs. It would be best to get an outboard amp though. It will not be as good as a powered sub. At least I don't think so.
Passive subwoofer...huh???
Ok, I am a dufus. I just bought an RBH VDS-10A passive subwoofer on eBay. I have a decent system; Threshold Forte Model 3A amp (200 wpc into 8 ohms); KEF Reference 103/4 loudspeakers; Parasound PLD-1100 preamp & Arcam Alpha 8SE CD player. Sounds fantastic, with the KEFs just a tad weak in the bass department. Didn't want a powered sub (too much like home theater, I thought), so I saw the RBH passive sub with its nifty 10" aluminum cone driver and said "Eureka." Naturally I bought it. No thinking, just bought it. Then it occurred to me; can I power it directly from my amp, or do I need a dedicated subwoofer amp??? If I drive it directly from my amp, should I run right and left channels into it (it only has one set of 5-way binding posts on the rear), or should I just run one channel?? Have I totally wasted my money?? I'm assuming the sub has an internal "crossover" to limit high frequency input, but I don't know that either. Doh!!! Help guys. -David (should be "KefKing" & not "Klipschking")