Check the listing for details. AEA RPQ503 500 Series Mic Preamp. Condition: Very Good - Refurbished. Listed at 719.10 USD. Versatile, High-gain 500 Series Preamp from AEA Derived from AEA’s 3rd-generation RPQ3 500 Series mic preamp, the RPQ503 delivers the same rich, natural sound, while adding a sweepable 2-band shelving EQ for quick, convenient signal shaping. With its ultra-low noise, low-distortion op-amps, high 68KΩ input impedance, and 85dB of clean mic gain, the RPQ503 serves up your microphone and line-level signals with pristine high fidelity. The RPQ503 incorporates the highly responsive EQ section of the AEA RPQ3, featuring LF and HF boost and cut controls on custom, dual-concentric potentiometers. With its prodigious gain, transparent sonics, onboard EQ, and budget-friendly price tag, the AEA RPQ503 is a performance- and value-packed preamp that can do justice to every mic in your locker.