Well, since journaling is a sort of file system log that keeps track of changes to the disk directory, if you are not copying, duplicating, creating or deleting files whether it is on or off becomes a moot point. So since you ask in the context of playback only, the advantages of journaling outweigh any possible speed hit, so it’s a definite “yes” to leaving it on.
After reading articles at apple.com and other sites, (which is probably what you read too… there is not that much out there)
This article talks about it from an engineering perspective, http://osxbook.com/book/bonus/misc/optimizations/
Also, Glyph (high-end pro audio drives manufacturer) itself recommends having journaling turned on for all drives. http://glyphtech.com/support/kb/questions/18/What+is+the+Mac+OS+Journaled+File+System%3F
Companies that understand the workings of it say to leave it on, and the recommendations to turn it off appear obsolete.