Hi Roloff,
I bought one of these earlier this year. With no other rivews to go by, I ended up spending quite some time at my local dealer in Seattle just listening. I really love the sound of this unit. The tubes just sound so right, especially after a good break in period. And we all know the price is excellent as well.
I learned from my dealer that the tuner stage and display are sourced from Denon. I am not sure what parts are involved, but now you know as much as I do. Like you, I have no idea how to shut off the following display anomalies: Cinema DSP and Surround Mode. I imagine Jolida could sell more of these tuners if they took the time to turn off those display items, since they give the idea that this is a surround tuner or something! My dealer had no idea, either, again stating that the items came from Denon.
However, I did sit down and figure out your "S" problem. When adding station call letters, just use a number 5 instead. The LED configuration uses the same five bars. When adding letters, just use the 5 key four times and you should end up on the 5 or "S" display.
To get the display to show the call letters, first you need to have them programmed in. Then, just simply click the "Display" button. Easy.
If you find any way to get those other display items out, let me know!
Hope this helps you. I sure am enjoying mine.
Brian