The Pros, cause theres no Cons.

The API 512C is a mic/line/instrument preamp designed to provide a low noise, unusually good sounding front end for all types of audio systems. Sonically, it is at the top of the "Mic Preamp List", regardless of price. Offering low noise (-129 EIN) and 65 dB of gain, the 512C includes phantom power, switchable polarity, -20 dB pad and Mic/Line or Instrument selector. Front panel XLR and 1/4 inch connectors combined with rear panel mic access allows for additional flexibility when installed in an API LunchBox, Six Pack, 10 position vertical rack, a 2 position horizontal rack, or an API console. What makes the API 512C unique is its long evolution from the original 1967 era 512, the first modular mic pre, to the current full featured 512C, while preserving the original sound character that made it so much a part of the early days of recording. Offering high headroom and a wide variety of inputs and input access ponts, it is ideal for unusual and demanding applications.
Imagine a situation where only a few preamps are needed, yet the smallest available console has a proportonally "small" mic preamp, making it useless for the demanding application, or conversely, imagine where you need a large number of preamps, and a console of sufficient inputs and quality would be too large to transport or rack mount. The 512C hits the spot with its quality and famous tone. Expand, combine or downsize at any time without trade-ins or product obsolescence. In addition, the 512C's sound and performance exceeds most "console mic pres" in every respect.
The beauty of the entire API 500 Series is its long term flexibility and lasting value when needs change over time. With a range of mounting frame options, the 512C will be a valuable asset to your performance critical applications.
The 512C Mic/Line Preamp makes use of the 2510 and 2520 op-amps and therefore exhibits the reliability, long life, and uniformity which are characteristic of API products.

Features

• Mic Preamp with 65 dB of gain
• Front and Back Panel Mic Input Access
• Line/Instrument Preamp with 50 dB of gain
• Front and Back Panel Line/Instrument Input
• LED VU meter for monitoring output level
• 20 dB pad switch, applies to mic/line/instrument
• 48v Phantom switchable power
• Traditional API fully discrete circuit design
• Uses the famous API 2520 Op-Amp
• Beautiful Colors