xLights is a sequencer for Lights. xLights has usb and E1.31 drivers. You can create sequences in this object oriented program. You can create playlists, schedule them, test your hardware, convert between different sequencers.
This is a VERY common issue that people bring up. Use Audacity to export the MP3 file with CONSTANT BIT RATE (CBR) and you'll be set. 128/192K does not matter.
When playing from the middle of the song in the sequencer and layout tab the waveform, output, and play head match up, but the music does not.
Playing from the beginning after hitting stop behaves normal.
If I want to preview a section I'm working on I have to play the entire song up the that point.