The two biggest sonic jolts I've experienced involving phono preamps were from two very different ones: the Petr Mares's Connoisseur 2.0 and Boulder's 2008, which was reviewed in the July 2002 Stereophile. The first was hand-built, single-ended, housed in a wooden case, limited to 100 units, and, when I got to hear it in the mid-1990s, cost around $6000, or about $10,000 in today's dollars. The other was a feature-laden, double-chassis monument to flexibility and surface-mount high technology. It featured beautifully finished, flush-mounted mirrored buttons your fingers just wanted to press.