I recently purchased a Hartke LH500 head and am running it thru a Hartke 4-10. Up til the other day the amp sounded amazing. Today I noticed that it took like 30 seconds before I could play thru it and it sounded distorted. I’ve never gotten the amp over 3 yet. I changed the 9v in my Ibanez SR655 and that helped a little bit there was still a crackle and an occasional noise or clip even when not playing. Before I send this back, has anyone else had this issue? Should I replace the preamp tube?