Kenwood KA 600 (1968–1970)

Name: Kenwood KA 600
Brand: Kenwood

A no-nonsense, overbuilt workhorse from Kenwood’s golden era—45 watts that punch like 80, with a phono stage that still flirts with moving coils.

Overview

Turn the volume knob on a Kenwood KA 600 past 11 o’clock and you start to understand why old-school reviewers called this thing “deceptively powerful.” It doesn’t scream or lunge—it just fills the room with a dense, articulate sound that feels like it’s coming from something twice its size. There’s no flash, no glowing VU meters or chrome trim, just a slab of black steel and a row of chunky switches that operate with the satisfying clack of a bank vault. This was Kenwood’s no-compromise approach to the late-’60s integrated amp: build it like a tank, spec it conservatively, and let the circuit do the talking. And talk it does—smooth mids, tight bass, and highs that don’t fatigue, even after hours of listening. It’s not as hyped-up as some of its flashier contemporaries, but it doesn’t need to be. Put on a well-recorded jazz trio and you’ll hear space between the instruments, texture in the cymbals, and a sense of timing that makes everything lock in.

Positioned just below the legendary KA-9100 in Kenwood’s hierarchy, the KA 600 was the sweet spot for buyers who wanted flagship-level performance without the flagship price. It wasn’t the most powerful amp in the lineup, nor the most feature-laden, but it struck a balance that still holds up: enough power for all but the most inefficient speakers, a phono stage that could handle low-output cartridges without a step-up transformer, and a build quality that makes most modern gear feel flimsy. The chassis is thick steel, the switches are industrial-grade, and the internal layout is clean and logical—no spaghetti wiring, no cut corners. It’s the kind of amp you could ship across the country in a cardboard box and plug in without missing a beat.

What really sets the KA 600 apart, though, is its phono stage. While most integrated amps of the era treated the phono input as an afterthought, Kenwood gave this one a fully discrete, FET-based front end with a three-position sensitivity switch: 2 mV for standard moving magnet carts, 0.5 mV for lower-output models, and a rare 0.05 mV setting that ventures into moving coil territory. That last setting is the real surprise—it means you could plug in a Grado “A” or an Ortofon SL-15T without a transformer and still get a healthy signal. For 1968, that was borderline radical. The rest of the preamp section is equally well thought out, with a tape monitor loop, a mono sum output (useful for AM radio or old mono records), and dual low-pass filters—one at 40 Hz and another at 80 Hz, which can be used together for a 24 dB/octave rumble cut. It’s not flashy, but it’s deeply practical.

Specifications

Manufacturer	Kenwood
Production Years	1968–1970
Original Price	Not available
Power Output	45 watts per channel into 8Ω (both channels driven, 20Hz–20kHz, 0.5% THD)
Dynamic Power (IHF)	170 watts total (8Ω, one channel driven)
Total Harmonic Distortion	0.5% (rated output)
Frequency Response	20Hz–50kHz (±1 dB)
Signal-to-Noise Ratio	87 dB (MM), 105 dB (line)
Input Sensitivity	2.5 mV (MM), 200 mV (line)
Input Impedance	30/50/100 kΩ (phono), 50 kΩ (line)
Output Level	150 mV (tape out)
Output Impedance	80 kΩ (tape out)
Damping Factor	29 (8Ω)
Phono Equalization	RIAA
Filters	Low-pass: 40 Hz and 80 Hz (12 dB/octave); High-pass: “For Scratch” switch (not specified)
Special Features	Three-position phono sensitivity switch, mono sum output, tape monitor, blue incandescent input indicators
Weight	24.5 lbs (11.1 kg)
Dimensions	440 × 154 × 388 mm (W × H × D)

Key Features

Phono Stage with Moving Coil Headroom

The KA 600’s phono stage is its secret weapon. While most integrated amps of the era maxed out at 2.5 mV sensitivity, the KA 600 offers a 0.05 mV setting—enough to handle some true moving coils without external gain. This wasn’t marketing fluff; service manuals and owner reports confirm that the circuit was robust enough to deliver clean gain at these levels. The FET input stage contributes to low noise and high input impedance, reducing loading issues with delicate cartridges. It’s not a dedicated MC preamp, but for a 1968 integrated, it’s astonishingly flexible. Even today, it means you can skip the step-up transformer and still get a balanced, dynamic sound from low-output carts.

Overbuilt Power Supply and Conservative Ratings

Kenwood rated the KA 600 at 45 watts per channel, but owners consistently report it driving difficult loads with ease—something that points to a stout power supply and conservative engineering. The IHF dynamic power rating of 170 watts total (one channel driven) hints at serious headroom, and the massive transformer inside backs that up. Unlike some brands that inflated specs with short bursts or single-channel tests, Kenwood stuck to both-channels-driven measurements, which makes the 45WPC figure more credible. The result is an amp that doesn’t clip harshly when pushed, instead softening the edges gracefully—a trait that makes it forgiving with less-than-perfect recordings.

Industrial-Grade Build and Serviceability

Open the chassis and you’re greeted with clean point-to-point wiring, high-quality connectors, and generous spacing between components. The power supply capacitors are large, the grounding scheme is thoughtful, and the entire layout invites servicing. Unlike later models that crammed everything onto dense PCBs, the KA 600 was built for decades of use. The front panel switches are heavy-duty, the volume pot is a long-life Alps unit, and even the speaker terminals—though non-color-coded and requiring a screwdriver—are solid brass with no signs of cost-cutting. It’s the kind of amp that, when properly restored, can last another 50 years.

Historical Context

The KA 600 arrived in 1968, just as solid-state amplifiers were shedding their early reputation for harshness and fragility. Kenwood, like Yamaha and Sansui, was pushing the boundaries of what transistors could do, focusing on reliability, musicality, and conservative specs. At the time, many manufacturers were chasing headline-grabbing wattage numbers, often using dubious measurement methods. Kenwood took the opposite approach: under-promise and over-deliver. The KA 600 competed with the likes of the Marantz 18, the Harman Kardon HK-630, and the Sansui AU-717—all respected performers, but few matched the KA 600’s combination of phono flexibility and build quality. It was also part of a broader trend: the rise of the high-performance integrated amplifier. Separate preamps and power amps were still the domain of the wealthy, but the integrated was becoming the serious audiophile’s choice for value and synergy. The KA 600 didn’t just participate in that trend—it helped define it.

Collectibility & Value

Today, the KA 600 trades between $150 and $300, depending on condition and restoration status. Fully serviced units with replaced capacitors and cleaned controls sit at the higher end, while untested or cosmetically rough examples go for less. It’s not as rare or coveted as a McIntosh MC240 or a Luxman L-550, but it’s respected among Kenwood enthusiasts and vintage audio restorers for its durability and musicality. The biggest risk for buyers is aging electrolytic capacitors—especially in the power supply and signal path. If not recapped, these can lead to hum, distortion, or even transistor failure. Service technicians observe that the output transistors (typically 2SC1452/2SA755 types) are prone to failure if the bias drifts, so a proper alignment is essential after restoration. The blue incandescent input indicators are another point of failure—simple to replace, but often missing or broken in unloved units. When shopping, check that the phono sensitivity switch clicks positively between positions and that the tape monitor loop works without crosstalk. A clean chassis, intact rubber feet, and original knobs add value, but the real prize is an amp that’s been properly recapped and biased. Done right, the KA 600 isn’t just a vintage curiosity—it’s a daily driver that can hold its own with modern gear.