Electrostatics - powering on/off -okay/not okay

I appreciate the quick and learned response. On - they stay. I have other questions I forgot to post.
(1)Can the longevity of electrostatics be affected by sunlight (direct/indirect)? My listening room is filled with windows. The light is indirect for most of the day. Yet, the western wall is all glass. So, the setting sun comes blazing in on the speakers- but at a lower intensity. I can close the blinds but prefer not to.
(2)The electrostatics that I just purchased were dealer demos that have been in storage for 6 months. Do they need to be burned in again? The reason I ask is because they are sounding bright. My system is fairly mellow - my previous speakers were the very revealing Infinity Renaissance with the Emit and Emin ribbons - and they sounded great. Even my Linn Kudos tuner is sounding harsh on these speakers. A speaker cable change might be necessary. Any thoughts? Thanks!

The learning curve continues steeply upward. Days later, I have powered down my Final Electrostatic speakers after 3 listening sessions. Each time, they had problems coming back up. One speaker didn't respond for 20 minutes. I need to consult with Final about this problem. Re: brightness, I spent a lengthy period of time with speaker placement. I did find great positioning for imaging but not brightness. I pulled out some ancient 10 guage stranded Monster Cable to see what would happen. Voila! Brightness gone. So, I guess my Mapleshade Golden Double Helix just doesn't mix with electrostatics. I think I'll give Innersound's speaker cable a try. I'm open to other suggestions. Thanks for all your help!