Heat cycling is less of an issue in today’s electronics as it was in the past so there are not significant concerns for component longevity. Furthermore, the design of the Ring DAC makes it immune to the typical tolerance fluctuations that electrical components go through as they age. All things being equal there is no benefit to powering the unit down vs. leaving it running constantly.
Temperature is an issue when it comes to the performance and stability of certain components when they are below their ideal temperature. This is especially true of the clock oscillator and certain parts of the output stage. These parts perform their best when at a constant and stable temperature.
Unlike a power amplifier your Bartók doesn’t generate a lot of heat, but it does have a very high thermal mass so it can take a very long time for internal temperatures to stabilise to the point that it’s in a state of equilibrium. Overall performance isn’t at its maximum level until the temperature of the unit has fully stabilised. Depending on the ambient conditions this process can take many, many hours.
Unfortunately, electricity isn’t free, nor is it in unlimited supply so there’s a real cost to leaving the unit fully powered-on all the time. Standby mode attempts to balance this by reducing the overall power consumption while allowing the operating temperature to remain close to normal operating levels. There’s still a warm-up time, but it’s greatly reduced when compared to a cold start.
If your unit sees frequent use (daily) then it’s worth leaving it powered on all the time or using the standby function. That way you’ll always be getting the best and most consistent audio performance. If it’s only used periodically (weekends) then it’s worth powering it down completely during periods of non-use, but being sure to power it back on well in advance of any critical listening.