I added a pair of FMR Audio Really Nice Compressors.

Two of them fit really nicely in this Funk Logic 1U rack panel.

The photo shows from top to bottom:

Furman PL-PLUS II Power Conditioner

Dual FMR RNC

Lexicon MPX-1 Multiple Effects Processor

Tascam SS-R1 Compact Flash Recorder

Each RNC is a stereo compressor/limiter.  I patched the first one (on the left in the photo) using TRS patch cords into the insert jacks of the first two inputs of my Mackie mixer, placing it before the signal goes through any EQ and before it is sent to the MPX-1 for effects.  The second RNC is patched between the mixer output and the recorder input.

Compressor effects are subtle, as they impact the envelope (amplitude) of the signal.  One reason I want compression is to get control over spikes in amplitude that can happen during auto-chaotic music of the sort that I make.  I also want to explore what kinds of effects they might be capable of.  The RNC has a side-chain path, which allows patching a filter or other processor between the input signal and the envelope detection circuit.  I plan to try this out with the left RNC, the one on the input side.