It should go mixer-->EQ-->amp. The Aural Exciter should be left at home, unless you have some very specific reason you need that kind of processing. And frankly, most contemporary recordings today (particularly the hip-pop/R&B stuff) are so disgustingly over-processed with that kind of effect, I cannot imagine why anyone would want to add more.
I agree with Mark - leave it at home! However if you insist, the order should be mixer -> aphex -> EQ -> amp. Why? Because the Aphex unit adds harmonics which otherwise might not be in the musical content and these added harmonics "might" cause feedback or resonance problems in the acoustical environment. If added in after the EQ, you've lost the control the EQ was supposed to provide in the first place.
Well, I will tell you my experince with my Aphex Aural Exiter. My first "pro system" was a Crest Audio VS2200 Amp, with a couple of SL-36 Cerwin Vega subs, and a DAS Audio PF-215 Speakers. All the system was in full Range. When I turned on the Aphex, the sound was improved a lot!. I love them, the bass was more notorius and deeper. And the speakers never were damaged, it is not a speaker destroyer because is not a subarmonic synth (that downs an octave the lows). The effect is likely adding a little delay to the bass.
A few moths later, I own a Crest Audio CA-12 and an Ashly xover to biamplifing my system. So with the same parameters in the Exiter, the sound was too muddy, the bass havent very good definition, so I change the parameters, and put the HALF of the effect that have before biamplifing.
Later, I sell the speakers and the VS amp, and buy DAS Audio Reference 218SUB and Raference 215 Speakers. Amps: Crest CA-6 for highs, CA-9 for mids and CA-12 for subs. This system really kicks ass. And the Aphex now, I had to have use it in the Big bottom effect at 10-20%. Theres a lot of difference without them, or overload the signal with it. I still use it, and I love it.
That I wanna try to tell you is that depends on your system the sound that you gonna have with an exiter.
About FeedBack, I never had problems with it, only if I put the mics in front of the speakers. If I had to, I had to turn the Exiter off.
Actually Nickie B already had answered the question...correctly I might add. The "Harmonics" processing absolutely needs to be before the equalisation, especially if you're doing much manipulation in the upper half of the spectrum. Putting the "exciter" after the EQ can easily lead to unpredictable results.
It would be a far better investment to save the money one might spend on an "aural exciter" (or some DSP wonder-toy that simulates the effect in the digital domain), and perhaps apply it to better speakers that you feel less need to "correct".
And finally, as someone who's very familiar with both BBE's and Aphex's, I can say that either of these devices "set in the middle" as someone else posted produces frighteningly over-processed high-frequency sound that is probably annoying people more than anything else.
The proper use of this kind of device is in the recording (or perhaps mastering) studios, *carefully set for best results with each piece of music*.
Mark's post is absolutely dead on! Nicky also correctly pointed out the correct place in the audio chain if one must run one of these devices.
Any of these devices as Mark noted can make a very poor speaker better somewhat...however, if using a quality speaker system and a good equalizer there simply is no contest...eq everytime!
I might further add, those who have been around audio a long time usually will advise one to forget the cheesy "Boom/Sizzle" effects these units produce and concentrate and true high fidelity that none of these devices can offer.
I have had an aphex unit for over 6 years and thinks it works and sounds great. I do however find it interesting that know one yet has indicated using a compressor limiter in the chain. Yes I know some of you out there use a drive rack but they have not been available that long. And I feel it will be one of the best $99 things you could ever buy. I recommend an alesis 3630. The gate will help with feedback. THe limiter feature is great when letting a cd play during dinner to keep everything at a constant level
My singal chain goes like this:
mid high amp
cerwin vega f-1 then to the sub amp