Kora Explorer 150SB integrated amplifier
Two grand gets you a microprocessor-controlled, remote-controlled integrated amp featuring two tubes, a 6922 and a 12BH7, coupled to a MOSFET output rated at 100Wpc into 8 ohms and 150Wpc into 3 ohms. The 150SB offers four line-level inputs, a tape-monitor loop, and direct access to the preamp and power-amp sections, should you wish to use the 150SB as a preamp with outboard amp, as an amp with an outboard preamp or a multichannel preamp-processor.
The front-panel controls include small chromed buttons for Power, Direct, Monitor, Input selection, and Volume up and down. There's also a front-panel–mounted ¼" headphone jack. An oval cutout shows the illuminated motorized volume control, marked in dB, and, when powered up, a glowing 6922 vacuum tube illuminated with blue LEDs. On the rear, gold-plated, Teflon-insulated input jacks are chassis-mounted and hardwired to the internal circuits, and speaker connection is via two sets of binding posts that accept spade lugs and banana plugs. Also on the rear are an IEC jack and the main power switch, a rocker type that lights up; when its in the On position, the 150SB is in standby mode.
Setup and Use
I placed the Explorer 150SB between my speakers atop the Ginkgo Audio Cloud 11 platform, with fewer balls than I'd used for the much heavier VPI Scoutmaster turntable. Sources were fed from my rack via long lengths of various interconnects, including AudioQuest Sky and Transparent Audio Reference, as well as Harmonic Technology's Revolutionary CyberLight Wave LAM Photon Transducers, which convert the line-level signal to light and transmit it fiber-optically to a receiver at the other end (review forthcoming). These are all expensive cables, but under typical circumstances source connections would be far shorter, and I didn't want degraded source signals traveling long distances to influence what I heard. Given the Explorer 150SB's modest cost, I used Analysis Plus Solo Crystal Oval 8 speaker cable—not exactly cheap at $963/8' pair, but an open- and clean-sounding cable, and I didn't think it fair to the Kora to go much lower in price or quality.
Loudspeakers were first the Wilson Audio WATT/Puppy 7s ($22,400/pair) and then, during the last few weeks, Wilson's MAXX Series 2s ($44,900/pair). That latter matchup might sound ludicrous, but it was an opportunity to test David Wilson's position on amplifier/speaker compatibility. At the 2004 Consumer Electronics Show, Wilson demoed a pair of Sophia speakers using an inexpensive Parasound amplifier hidden behind a curtain when listeners thought they were listening to expensive Krell monoblocks. His point was that a system should be built around good speakers; don't blow your wad on source or amplification gear.
Neither the Off nor On buttons on the remote control had any effect on the 150SB, so I turned it on manually. After a few minutes' warmup, the unit was ready to play, the 6922 tube glowing through the front panel like a log in a fireplace. The Mute button on the remote didn't work either, but the Tape monitor button did, so with nothing connected to the loop, I used that as a mute and lowered the volume to nearly off—I had no idea how much actual volume the amp would produce. For some reason, the markings of the Volume Up/Down buttons were reversed on the remote: the up arrow lowered the volume, the down arrow increased it. Go figure. At least I could use the remote to switch among sources: pushing Input 1 actually gave me Input 1.
Tight, compact, pleasing
When you're used to playing around with expensive, high-performance gear, it's likely that your expectations for a product costing a hair above $2k will be lower than usual. That doesn't mean you should be prepared for undistinguished mediocrity—there's plenty of that at all price points. But as the Kora Explorer 150SB proved, startlingly good sound and high performance in most (though of course not all) performance parameters are still possible at relatively modest prices.
Like the Whest PhonoStage.20 + MsU.20 phono preamp, which I reviewed in March, the Kora Explorer 150SB was an ear-opener. In some performance parameters it was spectacularly good—comparable to the best I've ever heard—though in other parameters it delivered far less than the best. In that "Analog Corner" I compared the $2495 Whest to the $29,000 Boulder 2008 phono preamp. Anyone thinking that the Whest would give them anything even close to the Boulder's performance would be disappointed, particularly in terms of its rhythm'n'pace and overall coherence. Still, the Whest did remind me of the Boulder to a surprising degree. Similarly, the Kora Explorer 150SB managed to produce a compact, well-organized, remarkably well-focused, three-dimensional soundstage with image specificity that an amplifier at any price would be proud to deliver. Ditto its rhythmic thrust and fast, punchy pacing. That's what visitors to my listening room—experienced listeners and novices alike—were consistently drawn toward.
The greatest sin a competently designed, $1995 audio component can deliver is a case of the blahs: nothing glaringly bad, nothing particularly memorable. Such designs basically have nothing to say, and having something to say is not dependent on price. For instance: A pair of Spica TC-50 loudspeakers ($600/pair when last available) had no deep bass, but they sure spoke volumes about soundstaging and imaging to anyone who listened, even if that listener was accustomed to speakers costing $50,000/pair.