I agree with the others that the only way to know with any certainty is to try it both ways, as many variables are involved. Including the technical characteristics of the particular components that are being connected, the particular cables, and the system, room, and listener. But as general rules of thumb the following factors will tend to work in the direction of increasing the criticality of an interconnect. And, correspondingly, in the direction of increasing the probability that the presumably "better" interconnect should be used at a particular location.
1)Higher
output impedance of the component driving the cable.
2)Longer cable length. Nearly all interconnect cable effects are proportional to length.
3)Susceptibility
of the particular components to ground loop issues, which is generally
not predictable.
4)Use of unbalanced rather than balanced cables.
Many audiophiles will assert that it is usually preferable to put the best interconnect as far upstream as possible, meaning between source and preamp. Their rationale being that the downstream components and cables cannot correct for inaccuracies introduced upstream. However, it is also true that the upstream components and cables cannot correct for inaccuracies introduced downstream. So regardless of how critical the upstream components and cables may be in any particular case, that rationale, although commonly stated, is not supportive IMO.
Regards,
-- Al
