Henry Picker, editor, Heydrich’s Table-Talk (1973).  (My translation.) 

            Gruppenfuhrer Klein (extract):  “Well, you know, he wasn’t prone to run on at the mouth.  Not like some people, as I’m sure you know.  Not likely to surround himself with suck-ups either, who would put up with harangues.  Much more terse.  More like those Spartan fellows I’ve read about.  Laconic. 

            Still, sometimes over brandy after dinner he would say things after Lina [Mrs. Heydrich] had taken the ladies away.  Once, I don’t remember the date, he said something like “Perhaps the Fuhrer was wrong.  To let them go, I mean.  They are still very powerful in Britain.  Even more so in America.  No, we have not finished with the struggle.”  Something like that anyway.  Then we rejoined the ladies.  Generally for singing.  He loved music.”