The Mastering Lab Studio Products Microphone Preamplifier matched pair. Only a few dozen hours on them. With incredible presence and sound, this Doug Sax designed microphone preamplifier has a clean-sound with warmth and richness that sits in the mix in a unique and classic way. Only a small amount of these pre’s were made and are a favorite among the industry’s best sound engineers; the preferred microphone preamplifier for vocals and strings.