Some of our headphone amps do not have tone controls. Many people would say that none are needed as they want the sound as pure as it can get. It seems that with many headphones you really can get a tonal change by moving the headphones around your head. Forward gives more bass, backwards gives more highs. I'm sure many will protest this way of changing our music sound saying that there is only one true placement of a pair of headphones. If any of you have not had a run at this process the results are more of a change of any new turntable or cd player. You can get a thick or thin sound just by the movement of one inch. It can make good phones greater on their way to great and make medium preformance headphones shine. It is just as important to the sound as speaker placement in a room. So to the many that know the epic result of this it may seem simple. To the masses it may be a sonic breakthrough! That's why we are hear. So in a field of endless tweeks this is the most simple and the most over-the top in results.