300B Warmup versus other tube or SS amps?


Anyone have experience in warming up their 300B SET amp?  My push pull tube amp comes on duty after about 15-20 minutes or so of warmup.  My 300B sounds distinctly better after 60-90 minutes of warmup.  If it's on for several hours it may even marginally improve from there.  It sounds a bit flat out of the gate (no warmup).  My other amps are not as sensitive to this.

I am just curious to what folks have observed in there setups.  
128x128jbhiller
I have Canary M350 mono's and warm them up for 10 min and run the system on low for 30 min. After an hour it sounds better. I don't know how long these amps are supposed to be warmed up before using. Love the sound.
Does a longer warmup time have to do with the amp being Class A?

For optimal sonics my Class A push/pull takes much longer to warm up than my AB amp.
 
 I ran (run) a Cary SLP 98P  Pre with a Cary V12R then a Cary Cad 120's and the manual calls for a 5 min warm up for the pre and 3 min warm up for the amps. Not sure on the Canary M 350's so I warm them up for 10-15 min. All the amps seem to sound better after 30 min.