There are different ways of getting natural reverb and natural echo
and you can do it in a variety of different ways like recording in a
large empty room without carpets and record inside Closed box-like
containers or steel shelves turned upside down or inside something
like a tank for a toilet that is empty or inside a steel chest box and
record inside stuff to get a ringing sound out of it and you can also
try recording in less populated areas of the street to get a vibe of it,
always try tweaking parameters with Equalizers and then try a little
bit of reverb from there and it should be interesting to hear the result.
You can get a Unison type effect with your synths by detuning the OSC
section so that one oscillator is center and the other is 1 percent higher,
or use your modulation section to create a unison type effect by having
the LFO section oscillate between two waveforms creating a unison type
of effect you can also use chorus for unison because unison is chorus in
a broader sense.
You can get crazy effects with vst softsynths emulations like arturia where
you have external modulation sections to do extra things with them or like
the Legacy Korg Cellection where the MS-20 has more then the original has.
I love the way softsynths are you can get a lot of cool stuff out of them but
when it comes to authenticity people whine about softsynts but I say there
are better if done right because you can save presets and sample them with
ease instead of saving over existing presets like some synths do or have only
storage capacities of expansion slot cards similar to PC cards.
I hope there will be more softsynth emulations of real synthesizers and also
of real drum machines and real instruments too.