Tactile is one of the most demanding things on an amp, continually used in only low HZ and especially if used on something like Simvibe with constant effects for bumps/engine/suspension. The Aura Pro are not very demanding, if anything one of the least and the ADX units while nobody ever bothered to open one up, to share on here I still expect the ADX models to be similar to the Aura Pro.
THIS
Parts Express still sell BK/Aura Pro not sure if Slick Cylinder just made a mistake earlier. They are one of the fastest I have ever used, they typically ship from USA-UK/Europe in 3 days. Import duty may also be added but your alternative is maybe finding European suppliers that might also ship worldwide. Although I doubt any cheaper than Parts Express may work out.
My advice is to stick to quality amplifier brands, I still cant recommend anything better than the inuke dsp that I am aware of at this time that has come to market but understand AUS prices for it may be higher. Really if looking comparisons locally your best bet is sourcing 4ohm PA amplifiers. These are what is commonly used by live bands, church halls (Public Address) and the music scene.
You will have websites for on-line sellers that specialise in this market/field and will stock reputable brands not just budget crap from china etc. Many such amps need to be heavy duty and reliable under continued usage. They are used to power larger subs or speakers but importantly these use 4ohm rating (same as most tactile) that is now very uncommon for home AV/Hifi speakers. The downside is many such amps may have fan noise for continued cooling and this includes the inuke series.
I personally can't recommend the SPL type amp as a quality unit. It may be fine for 50w Aura etc but the model I owned once had a supposed 700watt rating which caught fire under usage from my BK Advance at the time. The truth is however that a piston based tactile unit (Buttkicker/EarthQuake) require much higher demands from an amplifier.
Aura Pro ADX Clarke Synthesis all utilise much less. They also will operate with only a few watts, yet a BK Mini needs approx 50w just to start to operate (energy to begin moving the piston). As for noise even Berney Villers stated that the Clarke Synthesis and Aura Pro make more user noise. I am not referring to the piston over-driving or clacking on a Buttkicker but audible sound of the audio emiting from the tactile unit. You can address this with the DSP on inuke using the PEQ by lowering around the 60Hz+ frequencies
while not effecting others. It is not a Simvibe issue but how actual different tones when shifting out of low bass Hz begin to become more audible. They can be, if not addressed perhaps quite audible a bit like say low TV speaker volume might sound. I like it myself as it helps give the felt sensation additional presence, but more so in a stereo or directional configuration like CM. Yet lost with Headphone users.
Personally I would recommend
@Punknoodle or yourself goes for at least STEREO L/R tactile. It adds a good deal more immersion over just mono based effects, even multi-mono in pedals/seat. As example on a track like Spa with big kerbs that often you go wide onto or over you will feel both the Left/Right wheels independently go over and of course only directional bumps to the appropriate sides. This is much more satisfying than just a non directional felt vibration. Also gear changes and engine on multiple units rather than just one can have better dispersion of the effects throughout the users seat or say pedals.
*From my understanding if a user sets Simvibe to CM but sets "windows speaker config" to only STEREO then this will produce proper STEREO from the Simvibe Chassis for all games. If like you said via PM you may not be yet ready for full CM configuration.
These guys are a good example in UK/Europe of a music specialist store. They also stock Buttkicker under the "Fisher Amps" name. They usually are cheaper than UK Butt kicker dealer previously mentioned (Shaker Centre).
Edit: dude how many threads or you going to create regards this topic? 
