Raul, Yes, that's the way I would do it too. Use only a small value very high quality cap as a high pass filter in front of the amplifier that drives the upper frequencies. Then use a very high quality electronic crossover, with a steeper slope, to derive the low pass filter that drives the woofer amplifier. That's what I am doing with the Bev 2SWs, and I am very pleased. With a little fiddling, the crossover point is not audible. This is relevant to the topic, because by introducing the separate woofer/subwoofer, one is removing any rumble distortion from the main speakers without having to resort to a "rumble filter".
And yes, the success of that set-up has me thinking about adding a subwoofer to the Sound Lab system.
And yes, the success of that set-up has me thinking about adding a subwoofer to the Sound Lab system.