I have a Besson Sovereign 967 euphonium manufactured in England in 1992. I was told it cost about $7,000 when first purchased. Specifications are, bore: .580, bell: almost 12 1/4in although it's listed as 12in flat, and weight: about 9lbs 5oz from what I remember.
When I compared the Thomann 906 to the Sovereign, the Thomann sounds like a Prestige. It is bigger sounding (a bit "louder"), and darker than the Sovereign. I hear these differences in person and on my recordings. Both of these horns are top notch. My Thomann has the following specs, bell: 312mm, bore: .591, mine actually weighs 4.9kg (almost 11lbs) without anything added instead of the 5.1kg listed on the website.
The ONLY flaws with my horn are a few scratch marks inside the bell that probably occurred during production while it was being buffed.
I've played quite a few horns including: Antoine Courtois 167II, JP 374T Sterling, JP 274, Meinl Weston 551, and a Yamaha 642 clone. I believe the Thomann 906 Superior has the most beautiful sound. I want to add that all the horns I've played sound equally amazing and different. The Antoine Courtois probably has the darkest sound and the Meinl Weston probably has the biggest sound from MY experience.
It is a miracle you can buy a Thomann 906 Superior, that seems to be modeled after the older British style Prestige (Prestige used to have 12 1/4 bell, not sure how heavy it used to be while made in England before being made in Germany), at only a fraction of the price of even a JP Sterling! Not enough people know about this horn! I truly believe there can only be a slight if not less than that, difference between many of the top quality brands manufactured in China most likely, and top of the line name brand horns. I hope this review encourages someone to give this horn a try. Thank you, Thomann