definatly try a SMPS and get some of the great books from the upload down load sectyion including SMPS design handbook
i am big into audio amplifiers also . That would make a great final project. I would be willing to help and give my 2 cents
what level do you refer to when you say graduate project. do you mean say masters of engineering graduate project at a university?
SMPS have been around for a LONG time.. to do a project on this subject at the M.Eng level takes real enginuity! what will you do that is different? there is still some interesting research in planer transformers. good luck,