I offer a fantastic two channel microphone preamplifier Neumann V472-2   (TAB, Telefunken, Siemens)   in custom 1U design . This model contains high-end Haufe input and output transformers and has warm colorful sound especially for recording of acoustic guitar and strigs instrtuments. Preamp was modified to reach maximum gain of 60dB (instead of 40dB), but bellow 40dB works in the original electrical circuit   design (without change of feedback resistor in OpAmp circuit). This is provided by two packet 24 step rotary gain switch allowing  accurate gain adjustment (matching for both channels) with 2,5dB step.   If You have any other questions, don't hesitate to ask before bidding.