Tough one.
1. Noise reduction/his reduction first. You need to start with a clean signal. Unfortunately, a filter could be used here such as your eq to get rid of anomolies. An example would be a rumble filter for a turntable or hum. So, the order of your enhancers (spectral/adaptive) is up in the air. Assume for the MOST PART that an eq is for room acoustics. My pre-amp chain can deal with 10V inputs, most cant.
Then I would go with the stereo synthesizer. It would be out most of the time.
The sub-harmonic synthesizer is a bass enhancement device so it belongs in the eq category. Now compensate for room acoustics with the eq.
And finally limit/compress the output to the amp.
Your missing an dynamic range expander such as the dbx 1bx, 2bx, 3bx, 4bx or 5bx. (Old coveted equipment)
Yes, the order can be changed. Processors don't like to operate on noise. The eq is for room acoustics. It doesn't make sense to limit early, because the processors will change the limit, so it has to be last.
Make any sense at all?
I only have three processors: A FM multipath processor, a 4bx dynamic range expander w/ impact restoration. The impact restoration can make you hear say piano attacks on the strings and a 12 band graphic eq. A parametric eq would probably be preferred. A pink noise source and spectrum analizer would allow you to set up the eq properly. Usually the highs are boosted which means power has to be lower because those drivers are rated less than the woofers. 100 W vs 30 W. Freq response of the pre-amp/eq is 0 to 100 kHz.