The L1 is an 8ohm, non powered cabinet and can be used with anything that has a Nuetric(sp?) connector. ( not 1/4" )
I love that little ROland sub, and if I didn't have the Bose .... I'd be using exactly what Donny has. I even have a pair of Mackie 350's still in UNopened factory sealed cartons ... just in case I change my mind. (not likely)
The advantage of using the KC amps is the mixer. If you use a keyboard that has enough mixing on board, then it's no longer a factor. I send a mono cable from my psr3k into the Bose direct. No mixer needed, and it's been my favorite sound system ever. Some can't get used to it because they are listening to it with old, tried and true ideas. You need to embrase a NEW way of thinking. This system works differently than any other conventional system, and you need to be ready for how it works at peak efficiency. One tower, with one sub fills a room that holds 300-400 people without breaking a sweat. The volume is even and smooth, and there are no loud spots up close, and soft spots in back. It's very uniform throughout the room. People can talk without shouting - even if they sit right in front of it.

Boses recomends keeping it behind and about 6 feet away, but smaller situations don;t always allow that luxury. Even so .... I have NO feedback and I hear every note as clear as if I had headphones on. I'm VERY, very spoiled by how effective it is in so many different room configurations.

There's a pic of the setup on my website, with my antique kn7000. (long gone)