Speed Box is supposed to be an excellent product. It keeps the motor running at the perfect speed which can reduce the wow and flutter. Many people noticed a significant upgrade when using it, particularly if you have motor hum. I've debated getting this for a while, but my TT is very quiet so hasn't been a priority. This is all along with the obvious speed switching benefit. Kevin - did you notice audio improvement? Father's day is coming up so maybe I'll have the wife pick me up one..