Flipping record causing series of loud pops

Right. SOP- standard operating procedure. Business management used to like to call it best practices. Nike said, Just Do It! Whatever. Any way you slice it, beats the hell out of having to explain, explain, endlessly explain answering a zillion noob questions all to get back to: Just Do It!

Sorry, have never heard of a tube amp causing this issue. I’d say it is more likely a major build up of static electricity at the turntable platter. Maybe try zapping it with a zerostat. Is turntable grounded properly? What mat are you using? Felt can add lots of static. A leather mat works wonders...also the cleaning of a record while on a spinning platter can add lots of static, especially If using something like the old discwasher d4 system. The audioquest carbon fiber record brush seems to work well. 

Definitely static

Basic things!   
Baloney.  I never mute my phono in between.  There is no need to if everything is connected (grounded) properly.
If it wasn't static before it isn't now.  Doh.

If it is static electricity, you will feel the hairs on your arm raise when you lift the record off the platter no matter which phone preamp you're using. If this is the case, deal with the static discharge with one of the suggested solutions. Less likely, it's a grounding issue on your tube phono preamp.  Either way, get in the habit of using your mute button before cueing your tonearm down or up. That's what it's for and your amp will thank you.