Minimum volume control allows for the heel position to be set at zero up to 50% for any rhythm level. Gain control allows for the toe position to be set at 100% up to a boosted 20+ decibels of gain for powerful lead levels. Tuner output can be used at any volume, with any tuner, without any effect on audio signal. No high frequency loss at any volume. Works with active and passive audio signals. Can be placed anywhere in the signal chain. Improved sweep for ideal volume control, 9v batttery or DC adapter powered.