Kinergetics KBA-280 power amplifier:
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Comparisons
While the Aragon 8008ST is less expensive than the Kinergetics, the two amplifiers are naturals to square off against each other, not least because the Aragon remains my long-term reference for a relatively affordable high-end amplifier. Directly compared, it sounded more laid-back through the midrange and lower treble than the Kinergetics. Its midbass was less rich than the KBA-280's, and it sounded less liquid overall. These qualities gave the Kinergetics a greater presence, and more rounded dimensionality on vocals.

On the other hand, the Aragon was more open on top, with a greater sense of air and unrestricted extension. Its imaging was a little more tightly focused, its overall bass tighter. And while more sparkling on top than the Kinergetics, it was also a little more forgiving of excesses in the mid-treble. The Kinergetics was a little more subtle in its rendition of detail, warmer, and more forward-sounding. The Aragon, however, perhaps because of the latter quality in the KBA-280, rendered soundstage depth a bit more convincingly.

Balanced operation
Up to this point, all of my observations of the Kinergetics' sound have reflected its operation in the single-ended or unbalanced mode. There is a good reason for this. In its balanced mode, the amplifier's input impedance is 1k ohm. This was clearly a design choice rather than an oversight. But what it means is that the selection of a preamplifier to use with the KBA-280 must be made carefully. If its output impedance is relatively high, the amplifier's low input impedance will demand that the preamplifier supply current, something that many preamps are not designed to do.

I used the Kinergetics with the Jeff Rowland Design Group Consummate, which has a balanced output impedance of 300 ohms. Rowland preamps are designed to drive amplifiers with low input impedances. (Rowland recommends, in fact, that their own preamp/amp combinations be operated with the input impedance of the amplifier matching the output impedance of the preamplifier.)

With this caveat, the result I got from the Kinergetics in its balanced mode was a little surprising, and one of the rare cases where I've heard more than a subtle difference (or less) between unbalanced and balanced operation. Balanced operation with the Kinergetics tightened up the midbass noticeably, which further opened up the sound. Imaging was a little tighter, soundstaging more precise.

It still wasn't quite as airy on top as the Aragon, but it retained that sweet top end. The bass seemed more detailed in the balanced mode (very likely because of the tightened midbass). While the Aragon still had a margin over the Kinergetics in sheer power, I would definitely not be inclined to decide between these two amplifiers on the basis of their bass differences, unless my loudspeakers were very insensitive and needed the Aragon's higher power reserves.

Conclusion
The Kinergetics KBA-280 joins the Aragon 8008ST as one of my reference high-end-but-affordable amplifiers. It may lack the current retro chic of those esoteric single-ended triode jobs, and won't impress your friends with acres of heatsinks and backbreaking weight—but it doesn't disappoint in any way, either in its subjective listening quality or test-bench competence.