I can solve two of your three problems:
Problem number 1:
Veerstryngh Thynner wrote:I think I'm not going to pursue Tracktion any further. It looks fine, as far as I can judge, but it doesn't accept sfz and sf2, for all I can tell. I'd have to converse all my libraries to wav, and that'll create problems elsewhere.
Use Carla to play your sfz and sf2 files:
- Launch Carla. You can launch it standalone or as a plugin inside Tracktion.
- Behold the great white space in the middle of Carla's screen.
- Open a file manager and browse to your sfz and sf2 files.
- Drag and drop an sfz or sf2 file into Carla's great white space.
- Notice that a strip with knobs gets inserted at the top.
- Above that strip, there are three tabs: Rack, Patchbay and Logs. Click the Patchbay tab.
- You should see your sfz or sf2 file represented as a block/module. The name will be very visible so it's easy to identify it. It must have one or two output (blue) slots on the right side. Connect them to your system output (also blue). They may be called playback_1 and playback_2 inside a block called system, but I suspect those names may vary.
- Just hover your mouse pointer over the sfz or sf2 file module, so the piano roll will be enabled.
- Touch the piano roll with your mouse and listen to it.
- If Carla is running as a plugin inside Tracktion (or any other DAW for that matter), it should be ready to receive MIDI from a MIDI track inside the DAW.
- This is the Patchbay rack. Go back to the Rack tab, where you dropped the sfz or sf2 file.
- Click the icon of a wrench at the very top of the great white.
- Look for "MIDI Program" at the top. Those are the instruments available in the sfz or sf2 file. Browse and select.
- Click the Patchbay tab again and touch the piano roll to audition the instruments as you select them.
- Again: Carla can be run standalone or as a plugin inside any DAW, including Tracktion. Carla is a big Swiss Army knife that can solve many problems.
Problem number 2:
Veerstryngh Thynner wrote:the downloadable Tracktion version Tracktion offers for free seems to be Tracktion 5, not 6, as far as I can ascertain.
Version 6 is available right here:
https://www.tracktion.com/products/t6-daw
Problem number 3:
Veerstryngh Thynner wrote:But what I really want is to "play" musical instrument sample, on my desktop/laptop, on an electric guitar connected to my desktop/laptop, and hear a different instrument over my headphones:
Yeah, I know you want that, and I don't know how to do it. Maybe someone else can help.
Don't give up.