Ensemble is pretty unique. Not because it’s so great, but because it’s flawed in distinctive ways.
It’s designed to be a sort of super-ultra-chorus, using tons of delay taps in a carefully calculated way to make a whole orchestra out of, say, one string.
Instead, it sort of makes a Solina String Ensemble out of one string. The result is a totally different, and totally unnatural, texture. The depth of texture-smoothing you get from increasing the number of voices. Then, the Fullness control doesn’t really do ‘fullness’. Instead, it’s like sweeping a fixed flange, and at the top it sort of all merges together into a tubby and unpleasant tone. There’s a brightness enhance like with Chorus and Chorus Ensemble and the other Airwindows modulation plugs, but no real way to get realism out of it.
And none of that matters… if what you wanted was to get an unrealistic but slick wash of sound.
Use the Ensemble control as a ‘suck more lows out’ control. It’ll progressively make the sound leaner and more diffuse at the same time. More = thinner.
Use the Fullness control as a ‘slide the fixed flange’ control to voice the thing. It won’t want you to slide it while audio is playing, it’ll glitch. Set it for tone, not for ‘fullness’.
Use the Brightness to voice the top-end, and have fun with your retro-fake textures!