Adcom GFP-750 preamplifier Page 2
You'd think that designing a preamplifier would be simplicity itself, especially in these days of line-level sources. But the truth is, getting rid of a preamp's electronic fingerprint hasn't proven that easy—do a bypass test and the difference can be astounding. Preamps, even well-regarded ones, seem to compress dynamic range, muffle low-level details, and generally throw one of those much-talked-about veils over the sound. Some digital sources, like Wadia's processors and players and a handful of others, allow you to jettison your preamp, at least as a volume control, but you're plumb out of luck if you need to switch between multiple analog and digital sources.
The GFP-750 must be a disciple of Hippocrates, because it does about as little to a system's sound as any preamplifier I've heard—at any price. There is a slight—extremely slight—softening of details when it's used as an active preamplifier, but many audio cables have more sonic impact than the '750. So do most other preamps, for that matter. If you need to drive a long run of cable, or if you have a difficult amplifier impedance, I wouldn't hesitate to use the GFP-750's active circuitry.
In comparisons with the $1495 Audio Research LS8 (reviewed elsewhere in this issue by Martin Colloms), the active GFP-750 sounded considerably more open and extended. On discs with deep bass, such as Robert Rich's Seven Veils (Hearts of Space 11086-2), the Adcom quite simply captured the power and heft of the synth-produced bottom end in a way that the Audio Research did not. Without the direct comparison, I would probably have been quite happy with the LS8's bass response, but the Adcom had a lot more impact down under.
Nor did the LS8 reproduce the harmonic overtone structure of the recorders on the Flanders Recorder Quartet's Armonia di Flauti (CD, Opus 111 OPS 30-201) with the harsh and extremely extended—extremely alive—effervescence of the GFP-750. That harshness, which almost clangs, is what gives this fantastic-sounding CD its sparkle, but it was subdued by the LS8.
Again—while I clearly heard the Adcom as having superior overtone presentation in a direct comparison with the Audio Research, I did not find the ARC particularly closed-down on its own. It is not as transparent as the best preamps I've heard—which the Adcom is—but it is by no means among the most colored either. It's enjoyable, if not exemplary. The Adcom is both.
Actually, the preamplifier that most reminded me of the GFP-750 was the Mark Levinson No.380S, which costs $6495. The two had similarly open, grainless characters. In direct comparisons I had an extremely difficult time discerning differences between them—and that was a sighted comparison! Blindfold me and ask me to identify which one was playing and I'd probably have to flip a coin.
Unless the Adcom was in passive mode, when it was the sonic equivalent of nothing at all. What's it sound like? After many hours of listening, I'd have to say, "What did what sound like?" The GFP-750 is the preamp for the audiophile who hates preamps.
But if I had to describe the sound of no preamp, I'd say open, open, open. Open as in huge soundstage, uncompressed, naked—nary a veil in sight.
Not everybody prefers their sound so unembellished. I'm not sure I always do—sometimes a little euphony can be very appealing. That's okay. There's a lot to be said for liking something simply because it's pretty... But if you want to hear what the signal really sounds like, then the Adcom is the preamp for you.
Experiment treacherous, judgment difficult
But sometimes, judgment is simple. Adcom's GFP-750 is a remarkable preamplifier. It's well-built and elegantly designed—on the inside, where it counts. I've gone just gaga over it, not simply because it performs well for the money, but because it begs comparison with the best preamplifiers I've ever heard. Period. No matter how much you've budgeted for a stereo preamplifier, listen to the GFP-750 first. If you end up choosing something else, then you'll know that your choice is very good indeed.