Krell Industries KAV-250a and KAV-250a/3
Since their inception some 20 years ago, Krell has remained about as hard-core of an audiophile company as you're likely to find. Back in 1980, Krell shocked the hi-fi world with their enormous KSA-100. Since then, they have remained on the cutting edge of solid-state electronics. Just when you thought they couldn't push things any further, they would obliterate the competition with some unimaginably huge and powerful beast. The most recent example of this is the Master Reference series that they describe as being "mini-sized," but I think they must have been comparing the amps with a British car.
Therefore, it came as quite a surprise when Krell introduced the KAV series a few years ago—amplifiers that were fairly compact, were almost affordable, didn't double as space heaters, and yet were very powerful. The KAV 300i integrated amp was soon followed by a CD player and a line of separate preamps and power amps. Back in the November 1997 issue of HT, Brent Butterworth reviewed the KAV-250a and its matching KAV-250p preamp and was truly blown away. However, he did acknowledge that the two-channel system had little real relevance in the multichannel world of home theater. Now Krell has addressed this issue by introducing the KAV-250a/3, a three-channel brother for the two-channel KAV-250a.
Why would you want two separate power amps in a home theater system when there are plenty of great-sounding five-channel amps out there? Well, I can think of several reasons. Many of us use our systems both as a home theater and a music system, and—if you're like me—you'll want to listen to stereo music in its unadulterated two-channel form. Why then would you want to have three extra channels not being used when listening in stereo? Similarly, many of us place a higher priority on the quality of our two-channel music than on our home theater audio. With the Krell arrangement, you could use the three-channel amp for the center and surround channels and the even-better two-channel amp for the front mains. All Krell amps have identical sensitivity and output polarity to make mixing and matching easy. Additionally, some home theaters require more than five channels in order to drive a passive subwoofer or additional surround speakers. With combinations of two- and three-channel KAVs, you can come up with the exact number of channels needed for any type of setup.
As with any Krell product, build quality is as good as it gets. The solidity is such that I wouldn't hesitate to use the amp as a step stool if I needed to, although I'm sure that would count as misuse if you had a warranty claim. Balanced and single-ended inputs can be accommodated, and five-way binding posts are used for the speaker-cable connections. The two channels of the stereo amp and any two channels of the three-channel amp can be bridged, quadrupling the power output from 250 to 1,000 watts per channel into 8 ohms. Each amp has a trigger input; in an all-Krell system, you can connect the two-channel amp to be triggered by the 250p stereo preamp for two-channel listening, while triggering the three-channel amp with your surround processor for home theater use. To further aid in the integration of surround sound and two-channel stereo, the KAV-250p has a "theater throughput" mode that gives one of its inputs fixed gain by bypassing the volume control, so you don't have to worry about matching the levels every time you use your surround processor.