it’s simply a 3 knob delay pedal that has digital models of classic delay(echo) effects. Any delay pedal will produce similar results, but the classics that this one emulates each have their own character.
In any case, a delay pedal will add a very nice quality to any synth. Some prefer analog delays, but others might prefer a cleaner sounding digital delay. This one is digital that emulates some of both types, so it might suit your needs nicely.
I’m not seeing anything more than stereo and mono ins and outs. No expression input that I can see. Maybe I’m looking at the wrong version, but most delay pedals don’t have expression input.
I suggest running one out (L or R) from the A4 into the delay and then out to your amp or mixer. USe the other out to go straight into the amp or mixer. You can then blend the two sounds and it creates a much larger sound overall. That’s how I run my AR. Trust me, it’s awesome.