My experience has been, yes it makes a difference. Id say at least 24+ hours with my Primare A60 class D amp. I feel like it needs longer to sound good than my Pass Labs which is absolutely unexpected and I don't really understand why. But it's not subtle. Soundstage is more closed in and things sound less alive and real during warm-up if that makes sense.
On my pass A30.2 it sounds really good right off the bat and only gets slightly better on warmup. If bias were an issue, I'd think I'd hear more of a warm-up with the Class A? As that seems to be more commonly mentioned in audiophile circles. Just a note there. Just one person's anecdotal experience here. I recommend using your own ears and system to determine this. My amp is a purifi model I believe? An older one but the implementation sounded way better than better measuring amps on my system to my ears