Ive had the BHK 250 for six months and everything seems to be progressing nicely , I don’t think has run in as yet , it’s a little difficult to tell as I’ve been swapping out new cables and the BHK Pre arrived a couple of months back . Yesterday I turned everything on ( full hand of PS gear ) and after a minute or so there was a pop followed by some crackling and then I noticed the speaker cone in the left channel was slowly moving out in rather extended fashion as if there were dc being slowly fed to the speaker . I think I turned the pre down and then everything seem to return to normal and remained so for the rest of the day . Then the same happened again this morning . What do you think ?