Do you want to listen to the band, or do you want to be in the band?
Ages ago those were the rage; if you didn't like how the music sounded you could change it, but you always kept changing it until you had no idea what the original record sounded like.
If you're a music lover, stay as far away from those things as you can get; however, if you want to change the sound of every record to suit your personal taste, by all means get one.