split sub signal out of preamp to use 2 subs?

Hi everyone, I am using a Velodyne HGS-18 sub for home theater right now. I think the sub is a lot more than I need for my room. I have the sub volume nob turned up to only the second or third notch, and it is plenty. The room is 12W X 18D with a wall to wall carpeted wood floor. I read that it is better to use 2 smaller subs rather than one larger one, anyway, because it gives a better sound. However, my Classe SSP-75 only has one sub out, as do most. Can I split the signal in order to use 2 subs? Is that what everyone does that uses 2 subs? I am only aware of a couple of pre-amps that have two or more sub outputs? Also, what is the best small sub to buy?