Do you leave your SS amp on all the time?

John: My guess is that the amps that you speak of were were probably shoved into an enclosed rack, not allowing proper heat dissipation. These amps require open sides and at least 12" of space above them. Otherwise, you can expect them to cook themselves to death.

I have some of their amps with IGBT's in them also. They do not get turned off. My experience with circuits like this is that you have a greater chance of in-rush current smoking the outputs. On top of this, you now have tremendous thermal swings that occur over a relatively short period of time. This can result in uneven gain characteristics from output device to output device, resulting in reduced stability. Leaving the units powered up reduces all of the above problems to a minimum.

Obviously, one has to take into account that these amps will generate a good amount of heat and have them installed in a manner that will allow more than adequate ventilation. This is true whether the amp is cycled off and on or left on all the time. If placing the amp in a rack, keep in mind that heat rises. This will "warm" the shelf above it, which could transfer heat into the component above the amp.

If you are truly worried about such things, you might want to remove the top lid of the amp. This will allow greater cooling of the insides via natural convection. If you are worried about RFI or small fingers inside of the amp, it would not be hard to fabricate some screening that would act as both a shield and "guard". Sean
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Unless your amp has an "idle" feature, leave it on all the time. For the rear channels of my system, I use an old Marantz PM94 integrated amp, which is left on all the time. Everyone who I've ever spoken to who owns one of these things has found that they blow up after a period of time--the result of heat cycling. Not my PM94. It's been working continuously for nearly 8 years. Heat cycling is bad news for solid-state equipment.

Sean, thanks for the post. You make some valid points. I may try leaving it on. Ventilation is not a problem. My system sits on Lovan Sovereign AVR rack, which is 43" wide. The Threshold shares the top shelf with my turntable. So there is about 4+ feet of clearance between it and the ceiling. I always wondered what could cause those amp heatsinks to discolor so much. I thought it was being left on all the time or being run beyond their capabilities. I hadn't thought of poor ventilation, although that very well could have caused it.

Regards,
John

Stand by. Why pay the extra dough?

I keep mine on 24/7.

I put the NAD components into "standby" and the Plinius just stays on (per Plinius' recommendation and my listening pleasure). If I turn off the NAD stuff completely for a couple of days, they warm up in a few hours. However, the Plinius takes a frikkin' week! I'll never turn it off, unless I absolutely must (e.g., storm)!