Sound problem with LE and UA25EX and Vista

The UA25EX is an audio and MIDI interface between the computer and "the outside world".  It has two audio input jacks on the front which can be used to record audio signals into tracks in SONAR.  It has two audio output jacks on the back which can be used to convert digital audio from SONAR to audio signals that can be fed into a mixer or power amplifier which can then be sent to speakers so you can hear it (there is also a headphone output on the unit to drive headphones).  The audio outputs are not speaker outputs--they are designed to drive a line device (like a mixer or power-amp), not speakers.

Your soft synths need to have their audio outputs in SONAR sent to a SONAR bus or the SONAR master bus.  The master bus has its audio output set to send to the UA25EX.

If you have the soft synth playing back MIDI data and the track's outputs routed to busses routed to the UA25EX you should be able to hear the soft synth in your headphones.

You're most certainly welcome...I love to help.

Not that it can't, but normally audio or instrument tracks wouldn't go directly to the audio interface.   

Think of SONAR as a big analog mixer where you might have 32 channels, and each channel *can* be routed to a sub-mix bus, and each sub-mix bus *can* be routed to a master bus. 

This gives you flexibility in applying effects, or using buses for monitor mixes, etc.  Here is one example from a live sound mixing situation emulated in SONAR, if you have several different tracks playing drum sounds, you can route them to a single sub-mix bus, and if you have several tracks playing  brass (trumpet, trombone, etc) parts those can be routed to a second sub-mix bus.  And vocals to a third sub-mix bus.  Now you can control relative level of a group of tracks without changing their individual levels by adjusting the associated sub-mix bus.

So while you can assign the output of a track directly to the UA25EX, it is not normal to do so.  Route the output of the instrument track to the Master bus, or to a sub-mix bus which is then routed to the master.

Also, an softsynth instrument track (prior to SONAR 8) was really two tracks--a MIDI track and an Audio track.  The input for the MIDI track is usually your MIDI keyboard.  The output of the MIDI track is usually a soft synth audio track.  The output of a softsynth audio track then would be a bus.  In SONAR 8 and later, they introduced a simple soft-synth track that folded the separate MIDI/Audio track details into a single track view...but it can be represented either way based on preference with these newer versions.

So, it is important to make sure you understand the routing of Audio and MIDI through SONAR and the instrument and the interfaces.  You get a lot of flexibility which does increase the complexity.  If the routing isn't right you'll either get nothing or something which you don't expect.