2005 - 2009 Cadillac XLR: TechLink Article: Noticeable Difference in Audio Volume Level
Title: Noticeable Difference in Audio Volume Level
Source: GM TechLink Publication
Date: January 2012
On some 2006-2012 LaCrosse (Allure), Lucerne; 2011-2012 Regal; 2010-2012 Camaro; 2005-2012 Corvette; 2006-2012 Impala; 2006-2007 Monte Carlo; 2004-2012 Malibu; 2012 Sonic; 2005-2012 CTS, SRX; 2006-2011 DTS; 2005-2011 STS; and 2005 - 2009 Cadillac XLR models, a difference in audio levels may be noticed when switching between favorites/presets and/or audio bands. It may be noticed that the condition is happening when going between AM/FM, CD, and/or XM bands. Verify that the equalizer settings are all set to the same levels for each band when comparing audio differences. When storing the stations, it may also store the EQ settings. The increased or decreased bass and treble settings will enhance the level of noticed change.
In addition, try multiple CDs. This may be normal due to variations in the CD/MP3 burning process with commercially or consumer produced discs. If the condition changes with either the equalizer settings or multiple CDs, this is normal and no parts should be replaced.