This is from the API web site
http://www.apiaudio.com/3124.html

The model 3124+ utilizes the same microphone preamp circuit that is used in all API consoles. It uses the RE-115 K mic input transformer and the same output transformer that is used in all API equalizers. All four mic inputs of the 3124+ and the 3124M+ are powered by an internal 48 volt phantom power supply, front panel switchable for each channel. Also provided is a front panel 20 dB pad switch that effects both the Mic and Line in.

The model 3124+ can provide up to 65 dB of gain to an output clip level of +30 dBm. The Hi-Z front panel input goes directly to the op-amp, allowing a low level input such as a guitar or bass to be amplified without a matching transformer or direct box. This Hi-Z input can take input levels as high as +22, making it perfect for keyboards and other high level devices. The rear output is an XLR connector.

So, yes. And if you buy it instead of four individual 512c's, you save $400.

There is also the OSA stuff ( old school audio) that Nathan Eldred makes/sells. I'm not particuarly endorsing it but it might be worht looking at. I belive it is found at http://www.atlasproaudio.com