Red,
A lot of this is going to depend on what you want to do.

A software synth is just that, a synthesizer in software, instead of hardware like the VL70m. If I recall correctly, the VL70m is either monophonic or duophonic, i.e., it will only play one or two notes at a time.

The softsynths that you have talked about are polyphonic, and also multitimbral. That means they can play a multitude of notes (28 minimum for the General MIDI Standard) and can also play on multiple MIDI channels, usually up to 16 channels. Each channel may be dedicated to a different sound, i.e., piano, acoustic bass, drum set, jazz guitar, etc.

If you are not using a MIDI synthesizer as your output, then you may not need any of these synths. If you're using Real Tracks for all of your backing tracks, the soft synth isn't needed.

However, not everyone uses all Real Tracks all the time, so you may wish to have something like a string sound, which I don't think there's any Real Tracks for...yet. For that, you do want a synthesizer.

Getting the best quality synth is what it's all about. There are a load of free DXi or VSTi synths which can be downloaded, but Band In a Box usually likes to see a General MIDI compatible synth. Normally the VSTi or DXi synths, at least for the better ones, are a single instrument, and BIAB won't like that, however, you can use them in Real Band with better results.

My fave, inexpensive, Software Synth is the Roland TTS-1. It works with a 64 bit OS, is included in the Roland Music Creator package. Once you install it on your computer, you can call it up from within Band In A Box, or Real Band. The outputs will go through your Fatal1ty card. I might also recommend that instead of the Aux in that you use the Line In on the card, but that's up to you.

Gary

I'm blessed watching God do what He does best. I've had a few rough years, and I'm still not back to where I want to be, but I'm on the way and things are looking far better now than what they were!