Extended power on for Pass Labs XA.5 amplifiers

Has anybody experienced significant improvement in sound as your amplifier is left on for days? I was surprised to find how much can be extracted from Pass Labs XA 60.5 if they are left on for a long time. Unlike manufacturer recommendation, the first phase of stabilization in my case requires 4-5 hours at full power. The second phase is 4 days at full power.

I finally was able to leave them fully powered for 4 days, and today is the last and 5th day. That last ounce of realism at the mid range frequencies becomes available. But what's most pleasant to hear is that deep bass. Before this time, I could not increase the volume on the powered sub-woofer for each speaker very much without clouding the mid range and upper frequencies. Yet whatever it is that the extended power on has done to the XA 60.5, that extra bass just naturally fits into the rest of the sound. Concurrently that finer texture on the remainder of the music is certainly no triviality.