Changes in resistance should not make much of a difference if enough power is supplied. The BASH amplifier on the Klipsch 2.1s won't put out a huge amount of power, it's rated at 35W/channel. With double the impedence, you are looking at 18W/channel at 100% effiency (it's most likely about 50% efficiency, so you are looking at single digit wattage).
However, since the speakers are replaceable (I see them as low as about $20 new online) I personally wouldn't worry about blowing the speakers if you do indeed drive the amp to clipping.
You aren't likely to endanger the amp; the speakers are usually more vulnerable to underpowering/overpowering. I might add with a 120hz built-in crossover, the sound might not be that impressive (I've tried running various bookshelves off of MM subs. In general it's far removed from fuller sound you would get from running a signal down to 80 to 100hz.