Hmmm, don't have any 402's, but I do have a couple of sets of Bose 901's, a series II and a series IV (each comes with an equalizer). The equalizers are specifically designed to work with Bose speakers. I have played around with them some and discovered that on less expensive speakers they can dramatically improve the sound (they tend to increase the higher frequencies and the presence of the speaker, makes them sound more realistic) . But unlike other equalizers they are very limited in terms of adjusting the effect (or is that affect, I always get those mixed up:whatever: ) they have. I wouldn't recommend purchasing one without the speakers, but if you already have it, play around with it.