There's an old saying that goes something like this: "You can't make a silk purse from a sow's ear." Essentially, if the person does not have a marginally good voice to begin with, there's no vocal processor in the world that will improve it to the point where it will be considered good by anyone with normal hearing. However, if they can carry a tune, stay reasonably on key, the vocal processor in the PSR-2000/2100 will provide sufficient effects to make the vocals more appealing. As for the PA80, I have not heard anything good about their vocal processsor, and lots of negative comments from a few forum members who have used the PA80 extensively.
Good luck on whatever you decide to go with,
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)