I think a good A/B switching with zero lag would be the best way to hear jitter and describe exactly what it does to the sound
I can't do pefectly zero lag as the DSP amp takes two seconds to switch some pretty clunky relays - but this is close enough. I also would need to run it through my DSP amp as this has a multitude of inputs (toslink or SPDIF) and precise volume level matching capability. If the improvement cannot be heard through this DSP with AKM AK4382 192Khz/24 bit DAC's and a Crystal CS3310 analog attenuator and Burr Brown op amps then it is probably not worth the trouble as I would also need to upgrade this amp which is probably several thousand.
If I need to go to completely separate signal paths then it negates the possibility of A/B ing properly without moving and while seated at the listening position (with a remote in hand). If this were the case, then I am not really sure I could give up the convenience of the DSP unless the difference was truly impressive...