He starts by referencing the Ayre KX-R preamp with
and concludes withSo much for the effect of expectations on perception: the KX-R sounded better than no preamp at all! As Wes Phillips described in his review, music sounded especially alive through the KX-R, whereas with the Transporter driving the amplifiers directly, it was all a touch less involving; acoustic objects within the soundstage were all a tad less fleshed out.
But it could be argued that my finding should not have surprised me. Ever since reviewing Audio Research's groundbreaking SP-10 preamplifier in July 1984, I have suspected that the preamplifier is the heart of a system, that it colors and adds its own character to every signal that passes through it. What I hadn't anticipated was that this character might not be a mere absence of negatives, but could also be a positive attribute.
The XP-30 has rekindled for me the concept that the beating heart of an audio system is the preamplifier.