Typically it is best to use your PC's volume (soundcard or D/A interface).
From within Sound Forge, it depends on what version of Sound Forge. In most versions of Sound Forge Pro, the overall output can be boosted up to 12dB over unity (0dB) in "View> Hardware Meters".
I do not know if AS (Audio Studio) has this setting.

btw, welcome to the Magix Sound Forge users forum @Gary-Fujinami.