I'm surprised doing the reset didn't solve the problem for you. That may indicate that it is not a problem with the settings but could be a hardware problem.
If you plug headphones in do you get sound through them?
I'll just include the reset procedure for any other DSR-1000 users that may need it.
Reset Procedure
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1) Turn OFF the power.
2) Hold down the [4] and the [0] buttons on the 'Data Entry' numeric keypad, while turning ON the power to the Keyboard.
[This message has been edited by Nigel (edited 10-18-2008).]