From the Lumin owner’s manual:

Powering on

Running-in

LUMIN performs at its best after a running-in period (otherwise known as burn-in or break-in).

The duration can vary depending on the internal components, but under some conditions many users report that the sound continues to improve for a few weeks (200+ hours of playback).

Tips

• Using the LUMIN app you can create a mixed Playlist of different formats. Using music with different sample rates will utilise more of the internal componentry.
• You can put a mixed playlist on repeat and leave playing 24/7.
• During this time, it is best to leave cables connected to your other equipment, but the volume can be off on amplifiers.
• Even after the initial running-in period, leaving the system switched on can help provide a more consistent performance, especially just after starting.

But you know, you could always believe the flat-earthers on Audiogon who pretend to know more about electronics than the engineers who designed this equipment. 

good to finally see someone asking about break in

Tubes: On, no signal needed, about 60 hours (That's what Brent Jesse told me)

Vintage Equipment that has not been played for a long time:

start with low voltage, using a Variac. Progressively increase the voltage

i.e say 20 volts for 5 minutes, 30 for five, ..... until you get to a bit below ____ (it’s voltage rating) i.e. Japanese (100v) I stop at 90 v on the dial; USA (115/120 V) I stop at 100v on the dial.*

It’s not rocket science, just advised caution.

*Thus it absolutely does not matter if the Variac, new or old, is a bit off, say 5%, just start low, and finish below rated voltage. 

Thank you for the replies to my question. It really helps.

Just about all of my equipment has been purchased new, this is the first time in a long time that I have a new piece.

ozzy