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Amplifier Harman Kardon HK6550 review

The large rotary tone, balance, input and speaker selection controls all reflect HK’s very bold and purposeful styling. Unfortunately, its internal construction is somewhat messier. The use of fully discrete circuitry, even throughout its MM/ MC phono stage, is laudible enough, but the logistics of its layout could certainly stand improvement.

Otherwise, the HK6550 appears very similar indeed to the older HK6500, offering the same features and a similar high-current/low-feedback power amp. Nevertheless, its execution lacks the polish of the original.

Sound quality

It soon became clear that this amp has a distinctly grainy character which influences everything you play through it. Each note that sits in the upper midband is treated to a generous dose of fizz which has a significant effect on the way information is presented.

To begin with, this character was mistaken for detail, but as we worked through the various tracks it became clear that all was not well. The jazz track sounded relatively frantic and the various instruments lost their richness of tone, becoming dry and nasal. Joni Mitchell’s voice was treated to a dubious reshaping which made it sound more edgy, and the soprano sax made the uncomfortable metamorphosis into a kazoo.

Other limitations included an inability to reproduce dynamics. All the panellists mentioned how flat everything sounded.

The phono inputs provided a better sound, though one that was still troubled by edginess and unlikely to ever merit the appelation ‘relaxed’.


Not a success in either sonic or technical terms, the HK6550 seems to be a bit of a backward step for Harman Kardon, and hardly a worthy successor to the HK6500.

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