RamiNasr wroteTheoretically, yes, probably. 12V rail @16A = 192W max. The continuous power requirement of the XR 888 is 95W RMS (for 2Ohm speakers) or 60W RMS (for 4Ohm speakers).
However, continuous power is averaged over time. In reality, as you listen to music, the power draw of the speakers is spiking up and down very rapidly (typically thousands of times per second). The amplifier will try to filter out these spikes from its power supply input, but it depends on how good the filtering is, which isn't really specified. Car batteries are great at handling current spikes (there is a huge one when you start your car!).. computer PSUs, not so much. With loud death metal music (you know that's what you want this for :) some of those spikes will make it through to the 12VDC input, going well over 16A for very short periods of time. These will reduce the lifetime of the PSU.
So in summary it will work initially and it may even work for a long time if you keep the music volume reasonable. If you have nothing better to do with the PSU and don't mind killing it, this would be a fun project. Be sure to make this hack as water resistant and touch proof as possible.. use electrical tape liberally, put it in a ventilated box, etc. Good luck.
it is actually not that simple the power rating of an amplifier isn't just to divide the output RMS wattage by voltage.in theory this amp can take up to 100amps on 12vdc or 1200watt which is the unrealistic marketing peak power rating.
anyway the Boschmann xr888 is rated at 400watts Bridged output @2ohms or (380 non bridged 95watt x4 channels) you need to consider a power factor of let's say 0.6 at high volume so 400watts /0.6 = 667watts now 667 / 12v = ~56 amp @12volts.
but on average current draw will be around 56amps / 2 or 3 thats ~18-28 amps shooting to around 56amps at some points, on normal music tracks.
(these numbers are approximation, since some parameters are missing and power consumption of audio amplifiers because of its nature can't be accurately calculated)
in short no your power supply will not work at high volumes.