Hi Mark,
Thanks for the swift reply. Yes, I am able to hear both songs if I merge them. I noticed Windows Explorer gets the length right, while Media Player doesn't. I merged two songs with lengths of 4:01 and 4:29. Windows Explorer reports the length to be 8:31. Media Player playlist reports the length to be 16:30, but stops after 8:31.
It might be the Xing header as suggested confusing Media Player. Is there a way handle Xing headers in NAudio; preferrably by editing it, alternatively by skipping it. Will it for example be a single Mp3Frame, that I could just skip?