power amp question

[Elmo89m]

On ebay they have a lot of very powerful stereo poewer amps (like 2,000 watts) that go for around 200 dollars. Will these work, with a mixing board as a PA system? If not, why?

[petermiller]

what is the model + manufacturer of the amp in question.
A few words on this subject matter
Depends on what impedence the speakers are that you intend to use this with.
Ie most two way pay speakers are 8 ohm ea. In stereo you are looking at an 8ohm load per side of the amp. usually the amp model or power rating is either based on a flash rating as in consumer land or it will be advertized at a 2ohm or 4ohm load rating. say a power amp that is advertized to have 2000w total power. say at 2ohms @1000w per side. at 4ohms that might mead 700w or 600w a side and then at 8ohms that might mean 325 or 300w a side ore something like that. depending on what amp that is . so the amp that says it delivers 2000w might be an amp that gives you 300w a side into 2 8ohm speakers. Look at this when deciding to purchase an amp.
then what class of amp is it. is it class A a/b S d or so on.
any switching power supply would not be recomendable for subs or low frequency use. Due to the problem of no storage (capacitance) therfore not being able to recover from large ammounts of bass freq draw. Also what is the dampening factor is it >500 or <500 or something else.
take a look to see what you are dealing with
one more thing. what is the input sensitivity .07v oe 1.7 or 2.7 v or something else