Pretty much all 2.1 speakers connect though the sub to the PC, then to the satellite speakers. Many of them have an option to turn down the bass level though, check your speakers for that. Or you can use a graphic equalizer and turn down the lower frequencies.
No clue why having lower frequencies would cause you any issues, if the vocals do not have the range to hit the crossover to the sub, it won't get used. It's like wanting to take out your rear view mirrors till you want to see behind you in the car, then climbing out and installing them again.