Aesthetix Atlas question

I have the Atlas monoblocks, which I keep in Standby when not in use. When the units come out of Standby, the bass drivers of both speakers briefly (maybe 1 second) go to full or near-full excursion. I've had this happen with two different pair of speakers, both medium efficiency. Has anyone else had this experience, and should I be worried?
My Atlas stereo version does not do this? Great amps!
Not good. Volume all the way down?
Just happened last night. The preamp was muted and On for about 15 minutes before I started turning ON the Atlas. After about 10 minutes later, the left speaker suddenly produced an explosion sound. I rushed to turn off the Atlas. No smell. After waiting for another 30 minutes, I turned on the Atlas and this time, after it turned blue, I quickly muted the amp. There was a pop sound. I waited for about another 10 minutes and unmuted. Well, nothing..I could play that amp. Thank goodness!
Suggest you change the 2 6N7S tubes in the Atlas
 Best Johnnyr
Regardless of what you hear, if you see (with your eyes) excessive cone excursion as the amp comes out of standby, you need to send the amp back to Aesthetix for repair.