As you close in on a classic piece of kit you've been hunting down for weeks, the thrill of the chase kicks in. A nervous telephone call confirms the vendor is still in possession of your ears' desire. 

After a journey to some dark, distant location, there's the challenge of the haggle. The whole process is crowned (hopefully) by the triumph of a superb hi-fi component singing sweetly without having inflicted terminal damage to your wallet.

You know what they say about the best laid plans of mice and men, though. . . Buying second-hand hi-fi is like buying any other used item - if you know what to look for, you should be fine; if you don't, caveat emptor. What follows are not hard and fast inspection rules, but only guidelines to help those new to purchasing pre-owned. 

As well as the suggestions below, make sure you get a demonstration of anything you're thinking of shelling out for. Also avoid buying sight-unseen by mail, as this can be a very risky business. 

While we're on the subject, mixing and matching loudspeakers doesn't make for good stereo. It may be true that 'you can get them done', but don' pay anything remotely approaching serious money for a driver with a burnt-out voice coil or perished surround - for one thing you may never get round to it. Merely taking a 'speaker out of its box makes it second-hand, so ignore lines like 'only 30 hours' use'; it still isn't new. Many loudspeakers up to, say, 1970 had 15ohm voice coils so they may be quieter than 8ohm versions when plugged into your amp. 

Volume potentiometers have an annoying habit of becoming crackly as well, and switches are often in need of a good clean. If you get the chance to have a look under the lid, sure signs of an amp on its last legs are blackened or cracked high-power resistors and PCBs. When auditioning, as always listen to music you're familiar with. 

Another ploy is to carry around a portable CD player and interconnects whose sound you know well and use these as the source. This eliminates an extra variable in gauging the sound quality of the amp on offer. Low volume levels can give an indication of background noise, high levels will often unearth premature clipping or distortion. Once you start venturing beyond the 15-year mark, buying second-hand solid-state turns into a bit of a gamble. The transistors themselves get rather fragile, as do many of the passive parts.

It's far safer to stick to the reliable, household brands you've heard of. For novice buyers, it is wise to stay with 15watts/channel and under; generally such beasts are sweeter sounding and better behaved, even the mighty Leak coming to grief above this sort of power level. 

With most mainstream designs, finding new valves is the least of your worries and, although exact replacements for the reservoir caps are unlikely to be available, a little ingenuity and a trip to Maplin can get you out of most tight spots. In short, look to the transformers to give you the most grief. They CAN wear out as windings shake loose and are prone to internal (and thus undetectable) shorts if they've been overloaded. If a 10 watt amp has an output transformer significantly less than about 30 cu. ins. in volume, it is pretty unlikely to be high fidelity. Small is not beautiful with transformers. If you know little about valve equipment, don't be tempted to learn the hard way; the expression 'an amp to die for' should not be taken literally!

1) All-in-one (like the eternally popular Duals) where the arm and motor unit cannot be changed.

2) Removable armboard (like the Linn LP12/Roksan Xerxes/Pink Triangle Export) which gives a choice of partnering arms

3) Separate motor unit, plinth and armboard (like the Garrard 401/Goldring-Lenco 88/Technics SL-1000 MkII) which provides maximum flexibility. 

The caveats are pretty much the same for all three types. Moving parts are subject to wear and tear, which means the main bearing needs careful scrutinising. First, make sure the platter turns freely by giving it a spin. (This is easy with direct and idler drives, but you will probably have to take the belt off traditional decks.) If the platter slows down quickly, rotates unevenly or makes a grinding noise, steer well clear. Its rim should also remain steady when viewed edge-on. If it rises and falls obviously, there's likely to be a problem with the bearing. You can investigate further by rocking the platter's rim and checking for excessive movement. 

When examining a belt or idler drive ensure that, like the main bearing, the motor isn't heavily worn with the side-to-side test. It should run quietly too, although very few motors are completely silent. Idler drives can occasionally cause difficulties if the motor has been left in the On position. This can lead to a flat spot on the rubber idler, which can be heard as a regular 'thud, thud' when playing a record.

When it comes to listening, check for pitch stability, motor hum on spaces between tracks and high levels of background noise. 

1) Those with vertical and lateral ball races (such as Rega's RB250 and RB300);

2) Unipivots (Naim's Aro and Hadcock's 228, for instance).

A third group is air-bearings, but these tend to be rarer because the engineering involved in making them work properly carries a hefty price tag.

Check 1) by gently gripping the base of the arm with one hand and the arm yoke with the other.

To check for play in the vertical bearings, apply a light side-to-side pressure to the arm yoke. Use the same sort of kid-glove approach when twisting the arm-tube to see if the lateral bearings have any play in them. Unless it's suffered a fair amount of abuse, a unipivot is unlikely to have a worn bearing.

For peace of mind, you might try moving the arm-tube back and forward with a little light pressure - there should be no movement.

Scratched or mystery-unplayable CDs will give you an idea of what sort of state a machine's laser and pick-up are in. A lot of older specimens will have failing lasers and focussing faults which can be costly or impossible to correct. If the equipment refuses to read even your normal discs, you'd be better off passing it up. Unfathomable clicks and whirrings may also indicate servos which are past their sell-by date; most players should work quietly.

An old-timer may have mechanical construction superior to more modern 'biscuit boxes', but that doesn't automatically mean it will sound better. Digital output stages have come a long way over the last decade or so, as have decoders and clocks. Be prepared to shell out on a replacement masterclock and the odd mod or two if you want to discover the promise hidden behind the aged fascia.

A surprisingly common gremlin is having the panel lamps wax and wane with signal strength, presumably due to tired reservoir capacitors. Old mono tuners fitted with a multiplex output can be plugged into a stereo decoder such as Studio 12's. This arrangement usually gives better results than early (pre-1970) factory-installed jobs and, as mono tuners change hands for less dosh in the first place, there is a double benefit to be had. To be perfectly brutal, given a working tuner, the only significant criterion is sound quality - all the tuning gadgets in the cosmos are unlikely to make a Far East mega-blaster sound like a Troughline. 

As a very sweeping statement, give 99% of pre-Eighties stuff the go-by. Obviously famous brands like Nakamichi and Revox are a fairly safe bet but you need to ask yourself, with oodles of quality blank tapes still on sale (and new formats still not quite settled) why someone is getting rid of a perfectly good bit of kit. In spite of the slow speeds used in cassette mechanisms, things will wear out eventually, not least the heads and drive belts. 

A slack belt means wow at the very least, and biasing set for standard speeds will not function optimally with consistently slow tape travel. Assuming you're able to source one of the right size, a belt can take some extensive dismantling to replace. 

Another warning sign is when the plating on the heads is visibly worn down. However many tape formulations the deck is compatible with, be certain to make recordings on each setting to show up any defunct equalisation components. Again, if you have a portable cassette player, it's worthwhile taking it along to see that recordings made on one will play on the other!

Happy hunting!