Solid State Preamp Reviews

Talk about going from the ridiculous to the sublime. One day I'm reviewing the $139 Sonic Impact Super T power amplifier, and the next day Krell Industries delivers their $10,000 Evolution 505 SACD/CD player, $15,000 Evolution 202 preamplifier, and their $30,000/pair Evolution 600 monoblocks.

Compared to the Krell KSA-300S power amplifier that I also review this month, the KRC preamp's design is, at first glance, almost conventional. But its thoroughly high-end internal design has been equally well thought-out and executed. Its main, four-layer, glass-epoxy circuit board is for the audio signal, DC power, and ground—two layers for the latter are said to minimize noise. The gain stages are pure class-A and complementary. As in the amplifier, the circuit is direct-coupled, with servo circuits controlling the DC offset. The fully regulated power supply is housed in an external chassis. Seven inputs are provided: four single-ended, two balanced, and one single-ended tape. All inputs are line-level except for the optional, single-ended phono stage. (This review will address the line stages; a Follow-Up will discuss the phono stage's operation.) There are three outputs: balanced and single-ended main outputs, and a single-ended tape output.

About a decade ago, I read in Stereophile about the SRC, an add-on remote-control unit manufactured by Acoustic Research. I bought one the next day ('swhat happens when you work across the street from a hi-fi shop). Suddenly I was able to make incremental changes in volume and balance from my listening position—and let me tell you that that's the way to do it. What a phenomenal difference in realistic dynamics and soundstaging.

The KSL ($1800, $2100 with phono section) is a one-box line controller/preamplifier, just 2.25" high, with a nominal voltage gain of 10dB, or 3x. Despite its moderate price, the KSL is distinguished by having balanced outputs (via industry-standard XLR connectors), as well as two balanced inputs. Conventional single-ended, unbalanced outputs are also available via a pair of gold-plated phono sockets. Two unbalanced inputs are provided, plus a third via the tape monitor switch.

The roadster's throbbing rumble became a roar as the tachometer soared above 4 grand. Like a giant hand, its thrust jammed me back into the seat. Racing along low to the ground, feeling every curve and bump, I began to understand: the automotive virtues of smoothness and insulation had been swapped for firm road grip and the ability to transmit to the driver each jolt and curve in the surface below. Long before I'd climbed into the driver's seat of Porsche's Boxster S, I had known about its low-end snort and speed—the main reasons I was considering a lease—but I had not known about its ability to join sensation and purpose in such an intense bond.

This review should have appeared more than a few months ago. When I reviewed Linn's Troika cartridge back in the Fall of 1987, in Vol.10 No.6, Audiophile Systems also supplied me with a sample of the Linn LK1 preamplifier and the LK2 power amplifier, which I had intended to review in the due course of things. As it transpired, however, I was less than impressed with the LK2, finding, as did Alvin Gold back in Vol.9 No.2, that while it had a somewhat laid-back balance, it also suffered a pervasive "gray" coloration, which dried out recorded ambience and obscured fine detail.