[Elecraft] Noise-cancelling headphones mystery

[eric norris]

I have owned a pair of Heil noise-cancelling headphones for many years.  They worked very well to reduce the noise of my old AL-1200 amplifier, and the 5 fans on my cantankerous man-killer Henry 2002A EME amplifier.  However, they are completely ineffective against the KPA1500.  I bought a pair of Bose noise-cancelling headphones recently, and they work much better but are a bit tinny and eat batteries.
My question for the audio experts on this list is why don't the Heils work with the KPA1500?  Does anyone have a recommendation for a pair of really good noise-cancelling headphones with a more flat response? 
73 Eric WD6DBM

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