the data sheet tells more then the ebay link:
here is the real power specs:
4 x 50W/4Ω max.
4 x 30W/4Ω @ 14.4V, 1KHz, 10%
4 x 80W/2Ω max.
4 x 55W/2Ω @ 14.4V, 1KHz, 10%
though i see this as a issue:
Internally fixed gain (26dB)
this means that there is no way to adjust how the amp sounds-- so if you were to add a sub amp to this, you would not be able to adjust both correctly..
also, this line about standby is interesting as well:
STAND-BY and MUTING facilities are both CMOS compatible. In absence of true CMOS
ports or microprocessors, a direct connection to Vs of these two pins is admissible but a
470kΩ equivalent resistance should be present between the power supply and the muting
and stand-by pins.
R-C cells have always to be used in order to smooth down the transitions for preventing any
audible transient noises.
About the stand-by, the time constant to be assigned in order to obtain a virtually pop-free
transition has to be slower than 2.5V/ms.