The main sonic signature on the 2000 is derived from the use of the caps Parasound uses to bypass each electrolitic.
Upgrading those caps alone will help the 2000 a lot. Secondly, going through and replacing the metal film resistors with Vishay foil types will add more detail, depth, and drop the noise floor a significant amount.
Third, get rid of the walnut shell sized power transformer, and add an outboard 400-600VA type of your liking, toroid or E core. When you are done, you'll have an amazing sounding piece.
Fourth, replace the stock rectifier with a soft recovery type and replace the stock bypass caps with film and foil.
The sleeper of all time is their little Zpre. Sounds so-so stock, but once gone through, it becomes a true high resolution piece.
John