The K6 power module produces a very hot output, almost line level in some situations.
When the microphone is recording in a fairly loud SPL environment, the resulting audio signal from the K6 is too large for the camcorder's internal mic pre-amp.
The solution for this is to use the K6-CL power module. This version of the K6 has a reduced output level (approximately -14 dB) that will accommodate more sensitive mic pre-amps on some camcorders as well as other electronic equipment. You can purchase the K6-CL as is or, you can have your K6 converted to a K6-CL. The conversion will be performed at a charge of £30 + VAT