The Inward Connections 820 Compressor is a somewhat rare piece of outboard gear, that is only found when racked up custom rack like those made by Boutique Audio. We have a custom built rack with a few different pieces of gear from Inward Connections, with a chain that includes this compressor as well as the mic preamp and equalizer. It's all cased in a huge custom casing that requires it's own power supply. I don't know what the origins of this compressor is outside of Boutique Audio racking them, as it seems to be a custom only thing. The 820 Compressor is an analog piece of gear and you'd use the connections on whatever custom casing you had it in.
The configuration of the Inward Connections 820 Compressor isn't too hard to follow as it's a pretty basic compressor. It's got a small knob for gain reduction and a large one for make up gain. It also has switches for in/out, linking, and for setting the VU meter to either show gain reduction or overall output level. I don't know if there's a manual for this, but if there is I haven't seen it.
The tone of the Inward Connections 820 Compressor is absolutely outstanding. It's incredibly full sounding and will add a bit of body to just about anything your throw through it. I've only used the 820 for recording vocals along with the 820 EQ and MP (mic pre) as well, which makes for a pretty incredible vocal chain. The compressor isn't harsh at all and is great both for touching and signal and hitting it hard...
The Inward Connections 820 Compressor will certainly take an investment, as you'll not only need the module but a casing and power supply as well. The only situation where it would really be worth it to do so would be if you were also having some of the other modules like the EQ and mic pre in there as well, which is exactly the case with the one that I've used. Inward Connections makes some fabulous gear across the board, so if you're looking to build an incredible signal chain and price isn't your main concern, IC 820 Compressor and other modules are a must see.