Unfortunately, the transformer has not tolerate the new LED lamps for halogen. After a few days a transformer began to hum and has finally given up the ghost. We have now connected just 2 LED on a transformer and so far it fits again - no buzzing. But this issue is well known.
Believe it would not hurt if the transformers mittauscht equal, but for me the "old" transformers are installed in the ceiling and I just wanted to spare me the conversion.
The lights themselves are but top. To already numerous in-house lamps of sebson and am very happy with it, therefore also 5 star.