I just traded for an alpine 3554 4 channel amp. I printed up a user manual for it and it says the amp is... 50 watts x 4 into 4 ohms with 0.08% thd 750 watts x 4 into 2 ohms with 0.3% thd what does this mean? exactly how many watts is this amp? i have hooked it up and it does work great. is this amp worth having? and is it better than my 2 channel legacy blue diamond 1600 watt amp? any help would be greatly appreciated thanks