Meanwhile I saw some further video tests by Oluv (the well-known private tester on Youtube from Vienna) that clearly show that the Aiwa Exos is not extremely loud. It is slightly outperformed by the Teufel Boomster XL - and the Boomster XL is still not as loud as the Bose Sounddock 10.

Today I used my Beoplay A8 once again in the mid-to-large room in the picture (a registry-office wedding in a traditional rustic house typical of the "Münsterland" region in northern Westphalia). It filled the room with full piano & strings sound - not floor-shaking but really quite a big sound. It's amazing, it's just 4.3 kg (9 pounds)!