To sum up the Stereophile Recommended Components review:
The X-10 is intended to remove any mismatch between sourcedevice and amplification stage, the X-10 shows your CD player, DAC, or other source a high input impedence while offering your power amp, integrated, or preamp a low output impedence. Adding more depth and dimensionality to the sound, with more body and weight, the X-10 "brought the X-Ray's performance up to that of a world class CD player," said ST.Offers no gain, however, and has no control functions. "Stereophile rates it "Class A for what it is!" he sums it up.
For what it is? Huh