I've tried a few different Siemens 6922s and CCas, but eventually settled on the much cheaper Mullards. The Siemens were very transparent with extended highs, but sounded too lean in my system. The Mullards have a much fuller character with a slightly rolled off top end compared to the Siemens, but can match their air and soundstaging. After buying and liking a pair of these little cheaps guys I went back to the same seller and bought four more matched pairs. Couldn't be happier!