9Volt vs 18Volt Watch it in HD for best sound. This is what I hear when I up the voltage from 9V to 18V. All settings were made on purpose to highlight the difference. If your amp is pushing/compressing a little the difference will be less obvious. Also with 18V you get more level, if you compensate the difference will be less. Still I think this is a good example of what to expect when running on 18Volt. Basically the highs sound a little more "open", the lows are becoming less compressed, the perception of gain gets reduced and you gain a little more dynamics. There is no "best" here, try both and decide for yourself.