My JTV59 is on fw2.0 and it makes a popping sound when my HD500 changes the model selected when I change patch using Fs1 to fs4. I have tested the HD500 with a standard guitar and the patch changes are silent. I have also tested with the JTV and each patch set to DONT FORCE and its ok, but if the HD500 patch forces a model change then I get a popping sound when I press the Fs. I will roll back my JTV to an earlier fw and see if the popping disappears, and if it does then hopefully I can identify which fw introduced it. I suspect it was v2 as I did not have this problem before. This popping is particularly noticeable when connected up to my DT25 and also changing amp models, and at volume the popping is really clear and not what you want mid song or even between songs. Has anyone else had this issue? Thanks.