yes you can stap them, and they are rated at 900watts at 4ohms. VERY VERY under rated here is the specs from the site. They run at .25 ohms for full burps and .5 daily. One of the best ampsin the market. The customer service ***** (I heard) but still one of the best performance ampson the market. Do a search, you'll hear nothing but good things about this amp. Like 12 world championships this year in USACi. They have been tested to put out 8400 watts at .25.
Features
Digital class-D linkable mono block amplifier
MOSFET PWM power supply
Daisy-chain through output RCA
Heavy duty cooper layer double sided epoxy PCB
Stable into 1 ohm and 2 ohm parallel amplifier connection availability
24 dB low pass (LPF) crossover variable
18 dB bass boost equalization control variable
180 degree variable adjustable phase shift
24 dB subsonic filter variable
Selectable Switch for MASTER and SLAVE Operation
Speaker short, over current, thermal, and DC protection circuit
RCA line input and line output
2 x 0 guage (AWG) battery input connectors
Efficiency: 86% at 4 ohm, 100 Hz
Tested voltage & THD : 14.4V and less than 1% THD at 4 ohm RMS watt
Operating voltage: DC 10V ~ 18V power input
Damping factor: better 350 into 1 ohm
Wired remote controller
Specifications
RMS power, 2 ohm linkable/dual mono
RMS power, .75 ohms mono 5400
RMS power, 1 ohm mono 3600
RMS power, 2 ohm mono 1800
RMS power, 4 ohms mono 900
Signal to Noise Ratio >100dB
Low pass frequency crossover 35Hz~300Hz
Subsonic filter 10Hz~60Hz
Bass boost @ 45Hz 0~18dB
Phase shift control 0~180 degree
Frequency response 10Hz~350Hz (+/- 1dB)
T.H.D @ 4 ohm
Efficiency @ 4 ohm 86%
Fuse rating 500 amps
Input Sensitivity 200mV to 6V (+/- 5%)
From their site:
