I was wondering if I have seen a Balanced Adjustable with that combination of parts, thinking maybe. My quest for a true 156 got a bit crazy and I was buying loads of satin faced Balanced Adjustables from all over in hopes of getting lucky.
After looking thru a drawer full of B/As plus SP catalogs from that era including German, US, French, and Japanese versions... I think I agree with buddhasummer's evaluation of your find. A hodgepodge perhaps, but a good looking regulator with potential for great performance regardless.
As a bit of trivia, I think there are three numbers that apply to these type stages if strictly going by catalog designations. I'm sure someone will correct me if I have it wrong.
- Catalog # 109 is the original and unbalanced version. Can be upgraded to Balanced Adjustable status. Call these a 109.
- Catalog # 150 (or 152 if it was sold as octopus) accounts for 99% of Balanced Adjustables in the wild. Depending on when and where they were produced these have several factory combinations of adjustment knobs, bodies, and faceplates. Some have serial numbers printed on the body. Call these a Balanced Adjustable.
- Catalog # 156 is a very rare find, as it is the CE version of the Balanced Adjustable. These will have serial number & CE stamp on the body. I think these came in a couple minor factory variations. Call these "Da bomb"
The Mark X Dual Balanced is simply a factory re-labled Balanced Adjustable/MK10 combo. Aside from having Mark X Dual Balanced printed on the cover, the second stage is a standard Balanced Adjustable.