If you have a 2004 Altima contact 1-800-nissan1 and file a complaint about the stereo. If enough complaints are filed they will issue a recall to replace them. Now on to the issue!
The Bose stereo manufacturer on the 2004 was changed from Clarion to Panasonic (I think). The sound quality of the tuner in the 2004 is terrible! There are no highs at all and it sounds as if it is receiving a mono-signal. The CD player sounds fine with good quality. I recently upgraded from a 2002 2.5SL to the 2004 3.5SE. This was not a problem with the 2002 nor was it a problem with the 2003. I have had the dealer replace the head unit with the same model as factory installed and the problem remains.
Please, if you have a 2004 with the Bose Stereo file a complaint. Force Nissan to replace the poorly manufactured Panasonic stereo with the original one made by Clarion.
-R