Should Class A Amps be left on??

Well, I have tried leaving my Aleph 5 on for extended periods after all of this discussion and I must add that...

It is incredible how removed the amp becomes and music forward after one, two and even three days of power on. I am now sold on not turning off the amp overnight and only turning off for longer than 36 hour periods.

Other than the power bill the only downside I have come to experience is the desire for more dynamics that micro fade after extended power up periods.

In a word how does the Class A Aleph 5 perform after extended periods of power up, Incredible!

Sayas: Thanks for the follow-up. Hopefully, your posting of honest findings based on first hand experience will encourage others to check things out for themselves. It is good to see that, even though you initially thought your system sounded quite good, it sounds even better now. As you've found, it sometimes pays to have an open mind and experiment : )

As to the slight fading of dynamics that you are experiencing, i have to wonder if your amp is receiving adequate aiflow. It sounds as if the amp is running TOO hot, which can make them sound dynamically constricted in my experience. How much open space do you have on top of and around the amp ? I know that the Aleph's are all heat-sink, but anything that you can do to let the heat naturally dissipate through convection will only help the matter. Sean
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Sean, the 5 is in a basement on concrete, underpad & carpet and marble slab with nothing surrounding it for 4'. Airflow, cool air is as good as it gets. The listening room is 70F or cooler.
I am confident that the convection factor is as good as I can make it.

Leave them on...most decent Class A amps are designed with this in mind...if you have reservations....and want to turn them off...give them 10-15 minutes of "warm UP" when turning back on...and dont stack other componets on top!
If you have the old MF A1...you can make some chicken fajitas while listening to Mahler..awesome!

continuing this conversation after a time gap of roughly 19 years....

I recently acquired a Sumo nine class A power amp and Sumo Athena preamp. The preamp has a on/off switch that works but the powr amp on/off switch is broken. I currntly have them plugged into two independent surge protectors. I turn them on an hour or two before listening. 

These Sumo amps are 40 years old. I have no idea of their history.

I want to leave them on all the time, but of course they do not have standby mode.
I am afraid to leave them on while unattended.
But also worried about turning them on once every day, the sudden inrush current could damage the powr supply in the amps.

Any advise what to do in this sitatuion? Are there any reaaonably priced slow start/safe start for home audio? I only find lots of different options for surge protectors and power conditioners. Do these surge protectors and power conditioners protect against sudden spike in current while turning the switch on?
Thanks.