Leave Levinson on?

I leave my 335 on standby all the time. This way, the warm-up time is 5 to 10 mins. From full power-down (to my ears) the warm-up seems to be approx 30 to 60 mins.

I concur with Ikarus. I have ML 23.5 amps and leave them on 24/7 because I feel they sound better if I do. There is no standby setting on the ML 23.5 amp. There is a relatively sudden noticable improvement in sound (warm up time) after about 20-30 minutes with optimal sound being gradually reached after about 60-90 minutes. My ML dealer said that there is no problem leaving ML amps on 24/7 if you want to. Enjoy.

The Levinson now has a standby mode so it doesn't drain your pocket and gives you a rather quick start up for better sound sooner. It does not run as hot when you leave it on as say a Krell class A amp. Keep it in stand by and you will get the best of all worlds - money and sound.