Who knows origin and age of my sousaphone

[Geert.Drummen]

Liebe Musik Freunde,

I have bought recently below old Sousaphone, which has the inscription "W.H.Mann, Chicago, USA" on its 26 inch bell. However doing some research with the help of the experts of Tubenet it seems to be more like an A.K.Hüttl from Graslitz/Kraslice, or related.
Did somebody come across a similar sousaphone? Special is the Thumb plate. Broad protection plates. No serial number. As parts identification a "9." on bell connector and bell pipe (6.8 inch).

Best regards,
Geert Drummen, Maastricht, The Netherlands