And if you already have it set to volume you might be able to increase the value to a higher level e.g. "127" which is the loudest setting. Once the value is set you should be able to "write" the change so it saves the setting the next time you power on your keyboard.
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Yamaha Genos, Mackie HR824 MKII Studio Monitors, Mackie 1202 VLZ Pro Mixer (made in USA), Cakewalk Sonar Platinum, Shure SM58 vocal mic.