starting equiment that ic cold from being shipped

@feldmen4 Thanks for the gentlemanly apology Matt, but I took no (zero) offence.
And your expertise in the field is seeming more helpful than not..

@bossa

"My frost knee jerk..." I guess auto correct is warning me to wait
…

I was thinking condensation, so it is either auto-correct…
or
Maybe I pictured it being so cold that the condensation frosted up like a very cold drink?

If it was an auto-correct, then it must be the latest release of the auto-correct s/w, as it got it exactly right.

@bossa Early in my career I did thermal analysis - modeling problems just like this. I can tell you that it depends on the thermal properties of the materials the amp is made of. More or less the denser the longer it will take to come to equilibrium (room temperature). My 24 hour comment was flippant and was just reflecting your initial post. OMG that’s an awesome pair of components- just looked them up. The FPB is massive - and as you say “ long awaited”.  I would suggest 3-4 days but that is purely a conservative SWAG (scientific wild ass guess). I think this situation calls for being conservative - what is 4 more days after all the time you’ve waited just to get it right?

Regarding open box or not. All air contains water vapor. How much water vapor is in interior air depends on ambient conditions (outdoor temperature and humidity) unless the air is conditioned or humidified. For where @bossa lives humidifying air is common in the winter which would provide more available water vapor in the interior air. Even if they don’t humidify there will be much more water vapor in the air in the room than in the box. That means much more H2O that could wind up as condensation on the various cold surfaces of your components than is in the box. I have never received even a cheap electronic component that isn’t factory packed in a plastic bag with some sort of desiccant packed inside the plastic bag. That plastic bag + desiccant will keep your component nice and dry as long as the bag is sealed. Once you open it the desiccant cannot work quickly enough to protect your components and condensation will likely form.  As I mentioned in my first post if water vapor inside the box was an issue the condensation would have already formed during shipping as your components cooled. I guarantee you do not want to open the box during the warm up period. 
 

@agentwja - what you experience with double pain windows does not mean the water vapor in the house has been reduced. Rather that water vapor can no longer reach the cold inside surface of the glass windows here it would condense (just like on the cold surfaces of @bossa components). The cold inside surface is only exposed to a sealed area that is filled typically with argon gas to reduce re-radiation but it is also dry so there is no moisture ( water vapor) to condense on that surface (the inside surface of the outer pane of glass). The inside surface of the second pain which is exposed to the water vapor in the room is not cold enough for condensation to form - rather it is close to room temperature because of the excellent engineering of these windows. 

Regarding the cooling fins - yes they will work in reverse during the warm up but would only be effective if the amp is out of the box. However the fins would also increase air movement around the amp and thereby increase the likelihood of condensation. 

@feldmen4   Wow, thanks so much for this detailed analysis.  My balloon just popped however.  I've been awake for hours thinking that today is the day!  I have kept both boxes sealed as I completely agree that keeping things wrapped will hinder condensation.  I must tell you that the amp has been shipped to Krell 7 times between 2015 and 2021 for repair/recappping/etc.  It has been an audio nightmare, but I so love the combo of the KCT and the FPB 300CX that  I have refused to wave the white flag.  I'm pretty sure they don't pack it back with desiccant after repair.
Waiting 3-4 days seems like torture after so many absences.  I will say that Krell suggested 24 hours.  I spoke to a dealer in Milwaukee (Ultrafidelis) and I spoke to PS Audio who makes DAC and amps.  The tech said he got what i was saying but hadn't seen it as an issue in their business.  I will say that the Krell has many more parts than their offering.  The dealer said if your amp feels as cold as a bottled beer from the fridge, he would wait.  Any warmer than that and he said I could turn it on.  My plan is to do it in stages...first standby for hours and then on but not playing music for more hours.  Thanks so much for your input and expertise.

My logic is very simple as I'm a simple guy!

My point is to take it out of the box and put it in a garbage bag to prevent airflow and then put it in the warmest part of your house.

Many moons ago while in the military I was an Avionics tech working on jets.
So I have seen first hand where an airplane flies high and the aft equipment bay becomes very cold.  We were stationed in North Carolina a humid place. After  cycles of this some corrosion can set in causing electronic issues.

Your amp is not an airplane and won't be subject to freezing/thawing cycles.

Apparently you love this piece, so I would take all preventative steps.
This is just my two cents, but it is what I do.  Enjoy the piece, I hope it doesn't require any further trips to Krell.

Regards,

barts