LOUD music with LOTS of vibration will have the camcorder's internal hard disc drive heads parking to protect itself. That means no recording. This is not an "sound quality" issue, but a known issue with hard disc drives. The vibration causes the drop sensor to protect the hard drive platters. Turn off the drop sensor and plan on having the hard drive crash rendering the camcorder useless for anything than maybe a door stop.
http://www.docs.sony.com/release/DCRSR68_EN_ES.pdf
Pages 26, 47, 60.
Both are standard definition video cams - one's a bit newer. "Sound quality" is basically the same as they both depend on the internal mics and very limited manual audio control. Look in the manual
Pages 54, 66...
for "MicRef Level".
Most consumer grade camcorders cannot deal with loud audio - the automatic audio gain control gets overwhelmed and the result is muddy audio with static.
There's lots of reasons the pros don't use hard disc drive (consumer) camcorders...
The sr68 has an internal hard drive, is the sound capturing also upgraded or would it be the same as the sx45 ?
Application is Live Music.

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