Nakamichi's golden age was its mid-seventies 'ski-slope' cassette deck period, from where the 600 came, reckons David Price.

Back in 1973 cassette was, lest we forget, a 'joke format' designed by Philips a decade earlier for dictation purposes. It's hard to understate the importance of this company to audio's great pantheon - the 1000 went in and 'scorched the earth', changing everything. 

Suddenly cassette was a credible, high fidelity music carrier, capable of mixing it with top  open-reel decks of the day. The fact that it used tiny tape running at a measly one and seven eighth inches per second was mind boggling - how could Nakamichi squeeze a quart out of the proverbial pint pot? Accepted audio wisdom just couldn't have predicted it.

The 1000 was a three-head, dual capstan, two motor machine running Dolby B noise reduction and DNL (Dynamic Noise Limiting). This was impressive, but it didn't explain the stunning sound. The answer was the machine's supreme engineering depth - everything had been designed up to a performance level, rather than down to a price. 

The motors, transport and heads were all superb bespoke items that you simply couldn't find anywhere else - even an Aiwa OEM parts catalogue. This stunning bit of kit was partnered with the 700 Tri-Tracer, a downsized but only slightly sonically inferior machine offering Nakamichi sound to a few more buyers

In 1974, two new machines joined the fray. First was the 500 Dual Tracer, offering a two head transport for the first time, and the accompanying 550 'Versatile Cassette System' which was essentially a portable version and some say the first real 'Walkman'. 

The 500 was relatively short lived, for it was soon replaced by the 600 you see before you, which ushered in near-1000 levels of build and performance from a redesigned 2 head transport. A stylish new 'ski-slope' fascia - doubtless inspired by Mario Bellini's stunning Yamaha TC-800GL from 1974 - completed the picture. It was available in a choice of silver or black finished brushed aluminium and had an optional Perspex dust cover

The 600 cost £350, no small sum for any piece of hi-fi, let alone a cassette deck. As a gauge, a Linn LP12 would set you back around £294 at the time, so you can see this was no cheap machine. For such a princely sum however, you got absolutely mind-boggling, jaw-dropping performance. 

In the seventies, your average cassette deck struggled to stretch up to 11kHz with Ferric tape, and wow and flutter figures of 0.5% weren't unheard of - but the 600 offered 20Hz-20kHz and 0.09% (peak DIN weighted)! This was possible thanks to a superbly designed and made record/replay head and superbly aligned - albeit relatively simple -  transport. The final link in the chain was superb audio electronics which were as crisp and clean as was possible to find in any tape machine.

The 600 is fully configurable for either Ferric (EX) or Chrome (SX) tape. Metal tape for cassette use had not been invented and Nakamichi wasn't a fan of Sony's new-fangled FerriChrome formulation.  A built-in 400Hz test tone is provided, which in conjunction with separate left and right pots for recording level, bias and IM suppression (Nakamichi's proprietary intermodulation distortion suppression system) for both EX and SX tape, lets you tailor the machine to the tape with great accuracy. No other rival design offered such adjustment, and the result was an incredibly convincing sound, even by today's standards.

Set up the 600 for TDK SA and you get a bright, powerful and lively sound which doesn't just impress in the hi-fi sense but also in terms of musicality. There's so much energy you wonder how cassette could ever sound so bad on other machines. Bass is taut and powerful, with real slam and drive. Midband is wide open, with stacks of detail and strong image. 

Treble is deliciously crisp and atmospheric. In 2002 it sounds great, but in 1975 it must have blown people's minds! To put it into context, it's a far more natural sounding, and higher resolution recorder than, say, Pioneer's perfectly good PD-R609 CD recorder! 

These days you'll have to keep your eyes open for a 600, or its 600 II successor (from 1978-79, which adds a headphone socket to the formula). Still, you may be surprised by how inexpensive they are - this is because they're not the most prestigious of Naks (i.e. ZX-9, Dragon, CR-7E). You can pick them up for under £200 if you look hard. It's worth it though - no other deck offers the such a heady mix of brilliant sound and madcap seventies style.