Threshold 400A Amplifier and Conrad Jonson MF2500A

osirir just curious why does the title of your post mention the Conrad-johnson MF2500A?

Yes indeed. The CJ 2500a is a fine amplifier!

I'd be a little paranoid leaving the 400A on all of the time.  I had one and loved it.  The energy waste is huge so I only left it on if I was going to listen again in the near future. 
Why paranoid?  This is a fairly old unit and it well known that when they fail it can be catastrophic.  If they fry, it won't just be one transformer but most likely a whole bank of 8...
Use a surge protector if you aren't using a conditioner.  Also, have a tech check it out before leaving it on all the time.

Hi Jond. The reason was because I have a CJ MF2500 upgrade to A version and I was comparing it with the Threshold 400A. I love the MF2500, it is a sweet Amp. Chears

Hi Elevick. Yes that is exactly how I feel : paranoid: I'm using a Audioprism Mantissa power conditioner. I just got the 400A  and the previous owner had a full revision done in 2013. It is a great Amp. Is there any way to find out when it was build?. Thanks for your response. Osiris