I think you confused people as you said you now have an audio track that you don't like the sound of. Audio Plug ins are also called EFX plug ins.
VST are MIDI sound generating which is what I believe you are inquiring about.
Sonar comes with a large selection of VST instruments.
The TTS-1 is general MIDI multi channel so has those same sounds you find built into your computers sound card, but they have many enhancements using the GUI mixer you can edit the sounds and add efxs. There is a few bass sounds there, one is an acoustic bass but they are certainly not great.
Sonar has a virtual Bass plug in and there are a few free downloads at KVR web site. I was told "Broomstick Bass" is very good.But, sorry I've never used these things as I play real bass.