Originally posted by Hi-Liter:
Remember power is clarity 
Not so fast, trigger! :p
Signal integrity (not strength, don't confuse the two) always deteriorates or stays the same. There is no hardware on the market that can overcome a poor source unit. If there were, wouldn't everyone have one?
That being said, an amplifier only does what its name implies. Amplifies any given signal within it's operating range. You feed it a bad signal, you get an amplified bad signal. Throw more power at it, you get a louder bad signal. From entry to exit of any piece of hardware in a system, there may be alterations to the signal, i.e. the signal to noise ratio. Any alteration is considered bad.
I'm sure there's some obscure mathematical equation I could put here, but I hate math.
