I love the Ozone Stabilizer Cut mode. It works wonders on vocal-only tracks as well as entire mixes. When I use it for mastering, it often outperforms a de-esser and delivers the desired results. It allows me to filter out extremely harsh frequencies dynamically. The results are usually quite nice, whether it is a synth or a vocal. Use this setting: Adjust the "Amount" to decrease the gain by -1 to -3 dB.