I understand that this topic has not been bumped in 30 days, but I want to make a last effort for information on the EX-140 as this thread has some great B&K information. My searches have come up short.
The amplifier has a champaign faceplate and handles instead of the black. Details like the binding posts and placement of the RCA ins are different than the ST-140. The boards inside are ST-140 boards, but they are oriented totally different in internal space. There is also no serial number.
Musical Designs was able to confirm that the EX-140 exists and was not widely produced.
I have liked the amp, but I have not loved the amp. I wonder if this was not put into production and why it wasn't put into production.
Most hits out there are my questions on other boards.