Equalizers
A.R.T. (Applied Research and Technology) 355, available from sweetwater.com $189.97
2U high, 2-ch constant-Q graphic 31-band EQ 1/3oct +/-6 or 12dB. in:2xXLR, 2xTRS, 2xRCA. out: 2xXLR, 2xTRS, 2xRCA. This might be useable on a stereo. very versatile. could come in handy if you are using a spectrum analyzer.
Reverb
tc electronic Reverb 4000 stereo reverb processor with System 6000 reverb algorithms, available from sweetwater.com $2499.97
2U high. integrates with DAW using USB. 24-bit/96kHz. 134 presets/100 user. in: 2xXLR. out: 2xXLR. dig I/O: AES/EBU, S/PDIF, optical, word clock, MIDI I/O.
tc electronic M350 dual-engine reverb s/ software control, available from sweetwater.com $199.97
1U high, 256 presets/99 user. in:2xTRS. out:2xTRS (dual send/return). dig I/O: S/PDIF, MIDI I/O, MIDI clock tempo sync
Dynamics: compressor, limiter, gate
this is great for keeping your signals from blowing out your equipment, handling transients.
PreSonus ACP88 8-channel compressor/limiter/gate, available from sweetwater.com $899.95
2U high. in:8xTRS, out:8xTRS, sidechain. control vocals, tame drums, protect speakers, tighten low end.
dbx 166XL dual compressor/limiter/gate, available from sweetwater.com $259.97
1U high. in: 2xXLR,2xTS, 2xsidechain, out: 2xXLR, 2xTS