MIT cables and super tweeters

So I'm leaning towards purchasing some MIT cables (likely Shotgun S3 IC and speaker cables), but I can't figure out what the network box on the cables actually does. From what I've read, it appears to act as a low pass filter to remove all the grunge carried at utlra high frequencies which supposedly can muck up the audible frequencies. While this doesn't sound like a bad thing, I also intend to purchase a Townshend Super Tweeter (20kHz -70kHz per specs) some time this year (**crosses fingers**). If the MIT's network box is acting as a low pass filter, then wouldn't it filter out all the audio frequency info that would've gone to the super tweeter? Anybody have any insight on this as I'm not sure if this is even right. Thanks much.