While in the majority of systems I would agree with my learned Audiogon colleagues and friends who have suggested placing the long cable between preamp and power amp, in this case I’m going to disagree. Of course, as was suggested what would be ideal is to try it both ways, but if that is not practical here are reasons I suspect placing it between the phono stage and preamp is more likely than not to be the better choice, if it makes any difference at all (which it might not in this case):
1) The XP17 has a considerably lower output impedance (spec’d as 220 ohms balanced) than the Ref6 (measured by Stereophile as 612 ohms balanced at mid and high frequencies and 1378 ohms at 20 Hz). That will reduce sensitivity to some cable effects. Although the Ref6’s output impedance is still low enough to probably not be an issue with most 25 foot cables having reasonable capacitance.
2) Given the high sensitivity of your speakers, you are most likely using volume control settings which result in lower signal voltages at the output of the preamp than the phono stage is providing to the input of the preamp.
3) I suspect that neither component is particularly susceptible to ground loop issues (which can be sensitive to cable length). ARC designs for which I’ve seen schematics have a 10 ohm resistor between chassis ground and signal/circuit ground, which will help in that respect, and I would assume that Nelson Pass does something in the XP17 design which is at least as effective and perhaps more so.
Finally, I second the recommendations of either Canare or Mogami Gold Studio, which are widely used in studios and don’t cost a great deal. And keep in mind, as Jaytor pointed out, that as a general rule of thumb balanced interfaces tend to have less sensitivity to cable differences than unbalanced interfaces.
Good luck. Regards,
-- Al
