i've tended not to use the split oscillator feature much.
honestly, pull out a midi keyboard

get your octave jumping by working the octave knob.
you'll notice that at centre pitch you can detune in fine increments, and further away from centre, it's semitones. so you get your phatness in the middle.
you can almost sim PWM with LFO> pitch on a fast speed. if you have one osc an octave up from the other and a short decay -'AmpEG' on, Sustain off - it gets towards a 101 synthbass, very roughly.
NOW get a volca FM
i'm seeing them dirt cheap atm, still getting notifications of new ads. appearing at 80eu 2nd hand every few days. @
pajen
, volca firmware scion, has given it velocity reception and lots of other goodies, also fixing some Korg bugs, and it really makes a difference. ace little box.
also done one for Sample: check the volca sample firmware thread.
(and he said he'd managed to change the PCMs on the Beats - which means he might be able to add velocity to that one day)
considering everyone was talking about hardware mods when these first came out - twas the fashion then - rewriting the firmwares was not really an option anyone thought of.