Thank you for your comments. I have no use for the DXI because the soft synths sounds (Roland) are quite poor. Maybe there are good commercial software synths nowadays but I have only these that came with BIAB.

I realised what was wrong with my gear. I tried first to connect the audio cables from my Korg to the PC. Then I realised that I must use the firewire. I connected the audio cables from the Korg to the Terratec external sound cards "audio in". And now the synth sounds go through the sound card and firewire cable to the PC. An audio files are created properly!