As Randall mentioned I got to know the model quite well through testing its software, then setting up and using multiple Sub 25s in the factory's theater. I'm also familiar with the lineage beginning with the Servo 15 v1. Some clarifications regarding this thread:
Residential 120V circuits are almost always 15A or 20A and with that the Sub 25 amp can deliver 3000W to the voice coil's minimum impedance for a few seconds. After that the DSP lowers output so a dedicated 15A breaker doesn't trip. This intentional characteristic was modeled within a 15A breaker's time constant. With 208V or higher the Sub 25 can put out 3000W continuously. In North America 240V circuits and receptacles are used with window air conditioners and pumps. Converting a dedicated 3-conductor 120V (non-Edison) circuit to 240V is a minor operation, with a receptacle change and 2-pole breaker instead of single-pole (15A or 20A according to wire gauge, or typically 10A in 240V countries). If the outlet to be converted is not a dedicated circuit, it has to be turned into one - contact a licensed electrician. 240V is really not needed. With the bassiest music track that we use for testing subs, average consumption through the track is 800W if level is set so its peaks are at 3000W. This doesn't trip a dedicated 120V 15A circuit, and this is synthesized bass that is practically a sine wave.
With 208V or more the Sub 25 amp can actually put out 4500W but since the cone can't use it the sub is rated at 3000W, not 4500W. This is the opposite of how some other manufacturers rate their subs when amp power exceeds driver rating. Also, the Sub 25 power figures are real measured continuous watts, not "equivalent" power that some manufacturers quote based on amp performance with a lighter load - it's like saying a small car that goes 60 mph (100 km/h) uphill has an engine that puts out 500 HP when a 10 ton trailer is pulled.
Another factor in getting all this power is active power factor correction, which changes PF from around 0.65 to 0.99. All power supplies have poor power factor. Lower cost passive correction can take it up to about 0.85. Power factor represents the phase difference between AC voltage and current. The lower this is, the lower the real power because current can only flow while the voltage cycle peaks, resulting in a spiky current cycle instead of a sinusoidal one.
When on but with no input signal the Sub consumes 26W. If this seems low for a 3 kW amp remember that it's a class D amp with a switching power supply. When it's playing, consumption depends on how loud it's playing. When in standby mode the consumption was too low for the meter I used - probably well under a watt.
Due to high voltage inside a permanent grill was indeed needed to pass safety regulations. The certifications body later recognized that people aren't normally going to push things through the cone but what's done is done.
The SPL figures below are from anechoic measurements. For in-room response add 3 dB per nearby boundary, so if the sub is in a corner add 9 dB to all the numbers (that's where the data sheet's 125 dB of clean in-room bass comes from).
The Sub 25 puts out 9 Hz cleanly up to around 89 dB - after that it's limited by the DSP. We could make it go louder but it won't be clean. This is still better than not having 9 Hz response at all, and it's not like some manufacturers who say that if you input 8 Hz you'll get 120 dB out when what they're not saying is that it's loaded with distortion and/or containing no fundamental tone to speak of. From 17 Hz and up Sub 25 output is linear up to 108 dB. Beyond that the DSP rolls off the deepest bass off and the remainder goes up to 116 dB cleanly.
A proper setup and good source material says the rest.
Incidentally if you're using ARC, PBK usually isn't needed regardless of the number of subs (the greater the number, the more even the pressure around the room - it self-corrects). Just remember that when using multiple subs they must be balanced to one another before running ARC. This can be done by setting them individually to a reference SPL - usually below 70 dB each to account for the other subs - or by adjusting levels so peaks and nulls at the listening position set up by one sub are complemented by the other(s).
NOTE1: Subwoofer correction such as PBK only accounts for one sub at a time. The overall response is different when all subs play together, so overall correction in a pre-pro, such as ARC, must be run in a multi-sub setup after each sub has been individually corrected.
NOTE2: **Results can still be better if each sub in a multi-sub setup is PBK'd before running ARC. The only way to find by how much is to try both ways.
For more info the quickest way to reach me is to e-mail tech at anthemav dot com.