Can temperature fluctuations affect audio gear?

Everything in engineering is most likely C.
Another example would be heat and A/C.

If room temp is 70F and blows through a/c coil @ 40F great transfer.

If room temp is 70F and blows through a/c coil @ 60F little
transfer.

If room temp is 70F and blows through a/c coil @ 70F no transfer.

If room temp is 70F and blows through heat coil @ 120F high transfer.

If room temp is 70F and blows through heat coil @ 70F no transfer.

When transferring from more extremes,the transfer rate increase.This must be true,or our Heat A/C systems wouldn't work right,or at all.

HiFi.
Big is correct. Devices are apparently designed with a max junction temp at a given air temp. Lower air temp is gravey.

Read at least the written description of the math. It'll make sense. The heat-engine model doesn't apply where greater differences in temp produce greater results. transistor temps are sort of self-limiting and there are bunches of design criteria.

That being said, cooler is still better.

Sitting by a window with outdoor temp of 50F,little transfer
Sitting By a window with outdoor temp of 0 F,great transfer,
and it takes place both ways.At 0 F high rate of heat out,at same time,high rate of cold transferring in at 0 F.The more extreme, the faster the transfer rate.

As near as I can figure, that's the whole point. You'll have a zero difference when you fire it up with everything at room temp....BUT as soon as the device warms, it'll start moving heat away at such a rate as to maintain the calculated (or nearly) temp diff above ambient.
If you stick your room temp amp into the freezer, same deal.....just that now your working against the freezers ability to pull heat out (pump it) 'uphill' into the room....creating the cold box. Amp doesn't know this and will still end up warm VS the internal cold box temp.....and the same # of degrees.
If you put a power transistor in an insulated space and power it up,
you'll have a meltdown / failure in no time. No place for the heat to go. somewhere above maybe 150 to 200c, it'd just cease to function. These limits are all straight physics and chemistry.


But, based on the math the device will shed heat at a certain rate. Once it's been on and is stable, it'll run pretty much a certain amount above ambient for a long time. Even in the freezer......

This is pretty clear from the link I posted.
Also, find a datasheet. Somewhere is the 'derate' for power devices...and maybe others. The derate deals with power and temp. And how much less the device will take and at what rate, as it warms.

The OP? Long gone, but still and all, I'd not run my gear in an 85f space. Any weak link will be ruthlessly exposed. Any dry heatsink compound which isn't doing its job....a nut/screw securing a power transistor has come loose. A dust bunny clogging heatsink fins or some venting,.... All can hurt your stuff.

http://www.ee.latrobe.edu.au/internal/workshop/store/pdf/MJ2955.pdf

First datasheet I came across.
Look at figure #1 for temp derate and the bottom of page #1, just above the fig for the heat/ thermal #s.