cyeutter

This is a classic big synthesizer sound.  Think Oberhiem or something like that. All four slots are loaded with detuned sawtooth waves. 
Only slot four is set with a resonant filter sweep. Leaving the other three oscillators without resonant filtering allows for filter sweep without losing fatness.
Only slot one is configured for portamento.  This allows you to play fast figures using portamento without the sloppy sound portamento can sometimes give plus the nice effect as the portamento oscillator slides into tune with the others.  It’s an especially good effect if you’re running though distortion much like when a guitar player bends one string up to unison with another string that’s sounding.
Likewise, vibrato is only configured for one slot to get the growl as one oscillator cycles in and out of tune with the others.
Slider 1 - Intensity of the filter sweep
Slider 2 -  portamento time
Pedal 1 - toggles portamento off/on
Slider 3 – distortion
Slider 4 – chorus
Slider 5 – delay
Slider 6 - reverb
 
Sample audio contains a Christmas song snippet
 
 
https://soundcloud.com/craig-yeutter-586747245/big-synth
 

Not a string pad with piano. Fast attack and short decay string sound one octave above the piano to emulate a string section playing fast passages along with your piano.   Works best in the center third of the keyboard.
Slider 2 controls the strings one octive up 
Slider 3 controls strings in the same octave. In my opinion, fast strings in the same octave doesn't work as well as the octave up and can tend to sound more like a steel drum.
For fun, I try to include a Christmas song in my Soundcloud samples 
https://soundcloud.com/craig-yeutter-586747245/piano-fast-strings
 

Fast strings with lots of bow sound.   Add additional octave string with slider 3 
 
 

Erie and potentially aggressive electric piano-ish sound with a touch of filter sweep.