The AVR have problem in its pre amplifier stage. Normally this type of cracking noise will hear because of faulty op amp (operational amplifier) ics. To repair such problems you should have through knowledge in electronics. And also need SMD rework stations Beacuse all the op amp ics are SMDs. If yo have such knowledge then i have added here the link to the service manula for your AVR.
Refer the page number page number 13 first. Its the Audio section blaock diagram of the AVR. you can see the the suspected ic in the top right corner marked as IC410. Which is the pre stage op amp for the frond left righ amplifier. You have to replace this ic( integrated circuit).
You can find the position of the ic by refering Page number 27. Its the input board . On the board you can see three ics with 8 legs(four in each side) On the left side. You have to replace the ic marke as IC410. You can find the schematic for the input board in page number 26. the The part number of the ic M5218AFP-T .
Refer the sevice manual to know how to carefully to remove the input baord.http://sportsbil.com/sony/STR/STR-V/STR-V333ES_V444ES_V555ES_v1.2.pdf
If you need any more assistance feel free to conatct me through fixya.