Independent mono sampling.

Use a mixer with an aux send or alt output to the Toraiz input. Then you can sample whatever source you want without having to swap cables.

A mixer is an obvious workaround but an unnecessary one when the Toraiz already has a mixing environment onboard and one wishes to only plug in two instruments.  Additionally, once the Toraiz has live looping features (expected in firmware v1.4) the aux send from a mixer option would actually be less powerful than the ability to sample from two monophonic sources independently and directly on the Toraiz with only a few quick taps on the touchscreen.  Still, thank you for the suggestion.  It works for the Toraiz in its present iteration but in the long run I think people would like the option to split the inputs between two tracks.

From my vantage point mono sampling is a pretty needed feature for a few reasons. Most serious recording engineers limit their stereo tracks and keep things simple and focussed with the use of some mono tracks when mixing. Some instruments sound better and are easier to manage in a mix if kept mono. Now I don't expect the SP-16 to be a full fledged mixing environment but I at least want it to be a robust one for performance and production and to able to get tracks both stereo and mono into a proper mix environment from the SP. As much as I love the SP-16 there is currently a glaring flaw in its internal track architecture from a recording engineering stand point. Say I want to use one of the individual outs to help get a quality mix done from beats made on the SP-currently because all tracks are stereo, when using an individual out I can only feed half the recorded signal out, which is not optimal to say the least. The addition of a mono sampling mode would make it possible to take full advantage of the individual outs, as well as the full mix fidelity the SP should be capable of generating from a production standpoint. Mono sampling would also make it easier to use the SP as a portable sampling studio on the go-if I go to a percussionist, vocalist, horn player, or guitar player's house and want to sample them I would rather cary a small quality preamp/interface than a whole mixer. Most small mixers negatively affect the sound quality when tracking anyway so eliminating the need for them in the signal path really would definitely expand the sonic horizons of the SP. Having said all this I am constantly amazed by how much Pioneer/DSI got right with this box, its like they took all the best elements from all the coolest samplers I have owned over the years, got rid of most of the shortcomings,  and put it all together in one of the best interfaces of all time.