Replacing carpet padding?

[acr]

Has anyone replaced just the padding underneath their carpet? 

We're closing on a house & I noticed today that, while the carpet is in good shape, they must have used the cheapest padding underneath because it basically feels like walking on cement. Anyway, I don't think it's in the budget right now to totally replace the carpet, but curious if it'd be worthwhile or possible even to upgrade the padding.

[wavepool]

I was wondering this exact thing today, then remembered that the exact thing was done in our basement. You'd never know the carpet itself was pulled up and put back down.

[MrsDarcy]

Yes, you can just replace pad, then have the carpet restretched and reinstalled.