This is really more of a hardware update than a software update. The new code changes the configuration of the FPGA which can activate logic gates that have never been activated.
That said, I'm not sure how this would need burn-in since analog signals are not flowing through these transistors. I suppose it is possible that the gate switching timing could change subtly after burn-in which could theoretically change the sound.
I upgraded my Terminator + and was not crazy about the sound when I first checked it. I let it run for 72 hours with the amps off (so was not getting used to the sound), and did feel it sounded better when I listened to it again. But it had been a few days since listening to the previous version, so who knows.
If there really is a change over time, then I could see how no burn-in would be required by switching back since this will use the same logic gates that are well burned in since I assume the DAC was well run-in with the old code.
I sold my woofer towers just after I made the upgrade and am still waiting for the replacements. My main speakers only play down to about 170Hz so it's hard to make a final assessment of the new firmware until I have the new woofer towers. But I'm liking the sound at this point. I'm currently using the NOS mode which I always thought was a little dull sounding with the original firmware.
