D10 and HifiBluff, thank you both. I first got over the mechanical hurdle by building a mounting plate for AU90. The backplate for my M845s is spacious enough to fit a stainless steel plate to block off electromagnetic field from the bass transformer. Remember our sonic signals ride on the transformers. D10 if you can, I would very much appreciate to see a photo of the inside of you backplate so I can see the wirings (only when you happen to do the periodical checkup). Again thank you both.