We noticed an improvement on all tested microphones. A Shure SM57 for instance, sounds more responsive over a broader frequency range. When mated with a high-end dynamic microphone like a Sennheiser MD441, or Shure SM7 our FetHead really shines. Ribbon microphones benefit greatly too because of a much better impedance match. Fethead reduces the load on the microphone, giving it better transient response characteristics. FetHeads low noise signal amplification also extends the usable range of a ribbon microphone, making it more suitable to capture softer sound sources.