Harman Kardon's PM series arrived in 1990 riding the crest of a very specific moment: solid-state amplifiers had won the power war, but listeners were starting to miss what tubes did best. The company's solution wasn't to build a hybrid or hide behind marketing. They hired engineers who understood harmonic distortion as a feature, not a bug, and built Class AB output stages that could ring and bloom without sounding thin or analytical. The PM 655, arriving in 1995 as the mid-range integrated of the line, became the sweet spot—55 watts per channel into 8 ohms, enough muscle for real speakers, voiced with a golden-brown tone that made ordinary recordings sound like they'd been remastered in someone's listening room.
The 655 sits between the more affordable 430 and the heavier 680, and frankly it's the one people should be hunting for. The topology is Class AB across all channels, but Harman Kardon's proprietary feedback network keeps the output stage from going clinical. The preamp section uses a low-noise design that lets detail breathe without ever sounding harsh. Input impedance is high, gain is generous, and the signal path is beautifully short—you're not swimming through layers of switching and protection circuits. Listen to it next to a contemporary Denon or Marantz integrated and you'll hear the difference in the first thirty seconds: the Harman Kardon has a natural ease, a kind of settled confidence that better recordings reward immediately.
Build quality is genuinely solid. The chassis is rigid, the binding posts are tight, and the volume pot feels like it cost money. The front panel is understated brushed aluminum, no vacuum tubes glowing in a window, no false promises. The remote is a chunky thing from the nineties and it works. The toroidal transformer is oversized for the power rating—a sign that Harman Kardon understood headroom and dynamics matter more than wattage specs.
The real magic is in the voicing. This amplifier adds nothing you didn't ask for, but it refuses to subtract the good stuff either. Vocals sit forward without screaming. String instruments have body. Drums sound like drums, not like a click track. It's the kind of amp that makes you play records you've ignored for years because suddenly you can hear why they mattered. A well-recorded piano concerto becomes an event. A rough punk 7-inch becomes charming instead of fatiguing.
The honest caveat: this is not a high-current, low-impedance bruiser. It will struggle audibly with demanding speakers below 4 ohms or with highly inefficient designs. If your reference is a 200-watt Yamaha and you've got Magnepans, the 655 will reveal its limits. But with any reasonably efficient loudspeaker—Klipsch, Focal, Rogers, or even modest Spendors—it will sing. And at current market prices, you're looking at the same money as a new Class D digital amp that sounds like a Class D digital amp. The 655 sounds like someone cared.