Your topic, @Stan_Halen, is spot on- the art and magic of synths. I suppose there are virtuoso pianists who became more broadly keyboardists who at each level of synth technology created incredible music and new, wild sounds, some pioneering but many following their work.
Some were engineers and scientists who developed the hardware and software played by the musicians, sometimes the songwriters, and the arrangers, but altogether they produced art, and the magic of this new instrumental platform, out of whatever they had at the time. In the beginning it was a church organ, then an electric piano and a moog, a single note lead soundwave with portamento. Then the mellotron, a veritable string section in a box. And then the polyphonic multitimbral synths appeared, each with different approaches to create cool sounds. And yes, they had a lot of dials and sliders. Many would be set ahead and just played, some would be fiddled with in the playing, and the result would be a more complex sound.
I began with a computer, an Amiga 1000, a cheap Yamaha synth and Deluxe Music. With it I could program sheet music I wrote (mouse-clicked notes on bars) and could play the keyboard’s sounds via midi and also the Amiga’s 8-bit generated music. Although it was lo-fi, I remember how exciting it was to play Smoke on the Water power chords on my computer keyboard. I was able to play at least 4 different instruments at once, and I think only 4 or 6 notes at the same time, but this was already doing what few synths at that time could.
Alas, I had a Tascam and a Radio Shack 4 channel mixer to record with, and hiss was a terribly disappointing problem. We were trying back then to be desktop studios, but it was not so great on a budget.
But that early methodology employed the rudiments of layering sounds, and I think that is the bedrock of synth technique to this day. No matter how amazing the synths are that you have, the range of sounds become infinite when you layer them.
My first Windows 98 PC for music used Creative Labs Sound Blaster which came with Cubasis, the light version of Cubase which used soundfonts. This left my Amiga behind in the dust. Even the Steinberg Orchestra and Quartet soundfonts that came with it were amazing for orchestra sounds, a guitar, bass and drums, and then there were many freeware soundfonts, not to mention purchasable ones. The light was limited to 16 tracks, but honestly to this day I rarely exceed that.
But the available sounds were getting pretty amazing already, and pads were the first layered sounds with beginnings, middles and ends that evolved, much the same as big name hardware synths. The selection was not extensive, but what you did to take it much further was by layering them. You make your own pad with three or four tracks, and thereby one could have those cool swells tails and evolutions. I quickly began to treat one “instrument” track as a combination of several tracks all mostly playing in lockstep. I just read Pat Talbot saying recently here that even with Omnisphere he often layers more than one trumpet or piano or whatever instrument to achieve the richer sound he is looking for, and I currently find myself layering on almost ever new song.
What I do is create 8 to 16 note bars and copy them as needed for the basic song idea, and then I duplicate on other tracks with other instruments, and then I listen to them altogether or in any sets of them. I often try panning them as well. Recently I have tried automation to create cross pans of sounds, and you can see how that’s going. What you end up with can be a very complex synth sound, and at minimum a richer sound. Now often you do want that pure unadorned preset synth sound, but now it’s optional.
So what I’m saying, Stan, you can nowadays with Reaper really go to town with any synths all combined together into new custom sounds. Sometimes they are totally unexpected, sometimes layering sweetly and many times not so much, but you usually won’t know until you tried.
I think I usually have it in my head to sound like something I like, like Floyd, and trying for a synth sound that is similar, and usually I end up with something that sounds completely different, but there are many cases where that thrives and goes its own way, Floyd having to wait for a time.
For me, not a pianist but a sequencer, I see three groups of synth-
1- Humanlike piano playing
2- Possibly Computer Played melody chords
3- Ambient
They overlap, of course, but the first is written as if to be played by a human on a piano or keyboard. The second is more like a lead, arpeggios and chords, conveying character of whatever you can imagine, but not always trying to sound like it’s being played. Baba O’Reilly is a quick example of what I mean. The third is tones and beeps and buzzes, sound effects, rhythmic and percussive sounds.
So there is one goal of synths to sound indistinguishable from real instrument counterparts, but the other is to sound unlike real instruments, and that is the most fun aspect of synths. You can sit down at a Steinway and be awed, but when you play a synth it is magical.
It is cool to tweak a single synth sound, and there are times you will do that, and either you learn how to save presets if you can or just write it down so you can know what you did. I still don’t know how to do pitch and modulation in midi, it probably is easy, in Reaper, but that just opens up a whole new can of synth worms!
I felt like I was missing out on a musical element, and hope to stay focused on making usable tracks for composing. 
Playing guitar seems like a picnic compared to this.
). It seemed like a fairly realistic and practical way to learn the concepts with a significantly lower investment. I have their basic setup, but you can add many more modules at a small cost each (like $10) to expand the possibilities.