Got the 7mk4.Had a similar problem. Mine sounded like bacon frying w/o the aroma.Exchanged just the very front tube R/to/L.My center immage shifted.Not sure why that happened.Couldn't live with that. I re swapped back. While the amp was playing,I pushed down on this tube with a wiggly motion/ problem gone.Be nice if yours got cleared up that easy.
JADIS DEFY 7 SPIT SPUTTER
I AM EXPERIENCING A SPIT AND SPUTTER SOUND FROM THE LEFT CHANNEL OF MY Defy 7 amp after it warms up for an hour. this is not tube related. When I change left channel signal tubes with the right channel signal tubes, the noise stays in the left channel. All other components in the chain have been checked out. Any advice would be appreciated. thanks