If both the Linto and the line stage have selector switches, then it is an open circuit. If the Linto does not, and both output terminals are always hot, then the presence of the second set of cables presents a slight load at the Linto output, which is different for each cable set and can result in small differences in the total Linto output. You can test whether any of it is audible by listening to one pair of cables w/wo the other set plugged in.
As to the minor difference in pathway between two different sets of input posts or output posts which are switched on the inside of the box, I think you'd have to be very golden-eared to hear the difference (assuming good build quality), but the strict rules of A/B'ing say that you should use the same terminals. I suspect the cable differences will greatly exceed the minor differences from this source. After all, A/B switching boxes are built this way, though admittedly they should be built carefully.
As to the minor difference in pathway between two different sets of input posts or output posts which are switched on the inside of the box, I think you'd have to be very golden-eared to hear the difference (assuming good build quality), but the strict rules of A/B'ing say that you should use the same terminals. I suspect the cable differences will greatly exceed the minor differences from this source. After all, A/B switching boxes are built this way, though admittedly they should be built carefully.