[Elecraft] K3 weak rx audio when AFX is NOT active?

[Sam Morgan]

I just added a different set of stereo amplified speakers to my K3 #4123.

Yesterday all was ok, if I switched from AFX active to OFF,
my volume levels remained the same, just the sound changed.

Today I was listening with the AFX BIN active (my normal setting)
and then I switched the AFX OFF, and my volume level dropped way down.

If I listen through my headphones, the volume level stays the same.

Have I killed my audio out?

Why would volume still be ok on both speakers and headphones when the 
AFX is active if it the dreaded 'killed my speaker amp IC chip' problem?
-- 
GB & 73
K5OAI
Sam Morgan