Expert 1000 Pro

[srima]

I wonder if the increased temperature applies only to the class A amp or the entire device. Maybe running  the class A part hotter makes it more linear and still could reduce the powerconsumption of the entire amp.

To summarise from my earlier post, on the same (very hot!) day, with the same speakers, very similar volume, the D800 was running A=43° D=42° S=41°, the Pro was reading A=57° D=48° S=50°.  That does not look more efficient to me.  It did sound good though! 

These high temperatures should be a cause for real concern. They suggest a product that may require frequent servicing to keep it going for the long run. I had a Krell KCT preamp for a few years. Gorgeous preamp with no solid-state harshness, but a full lush sound. Problem was that it ran incredibly hot, with the output transistors in class A mode. Even in standby, it felt warm. After a couple of years, I kept having trouble with it, the display would freeze, the remote would stop working, everyday some new problem would surface. I finally sold it in frustration. 

High temperatures are not a cause for concern if the product has sufficient heat dissipation capability. My Krell 700cx runs quite warm, but has massive heat sinks across its large body on either side. Even so, the heat generated is sufficient that the Krell would often make clicking sounds, which the factory said was normal. This was the  metal casework expanding and contracting, as the amp warmed up or cooled down. The 1000 Pro's don't have heat sinks, they must dissipate the heat through their surface. Perhaps quiet fans could be installed that blow air from top or bottom on the 1000 Pro's. 

As a computer science professor, I recently built several high performance GPU machines where heat dissipation is a huge concern. My first machine  used the powerful Tesla K80 (24 gig) graphics card, which lacked any internal fans, and was passively cooled. The Tesla was intended to be used in high performance servers, with loud powerful fans blowing over it. In my machine, it first ran for 10 seconds, overheated and shut down. It took me a few weeks to install a bank of fans all around that keep it cool enough to run long simulations. The Tesla is designed to withstand temperatures in the high 80s and lower 90s (centigrade), which is hot enough to burn your hand. My favorite current cards are the EVGA Titan X hybrid cards, which never get warmer than 40 degrees ©, even at full load. 

For a class D/class A amp to run around 60 degrees © is really surprising. I have a Quad Elite amp (latest variant of the classic Quad 606), which uses current dumping, combining a class A amp with a class B amp. It never runs more than slightly warm, even at loud volumes.