QUAD II amplifiers are one of the most popular items bought on eBay. 

Here are a few pointers that might be useful.

Buyers tend to favour amplifiers with very close serial numbers but this is not really necessary. The design of the amplifier never changed and unless the serial number is below 8000 the circuits and components will be the same.

Pre serial number8000 QUAD experimented with transformers so there were a few variations. However it would be an incredible ear that might detect any difference and I doubt that anyone has such ears.

The serial numbers are on plates so just because they are consecutive does not mean the amplifiers were consecutive as it is easy to swap plates between units.

The one thing that did vary a great deal with QUAD was paint colour. There are many variations of the battle ship grey which was used so getting two amplifiers which are the same shade will be most difficult and because they do not match should not put buyers off.

This paint shade issue actually goes for much of the early QUAD HiFi including the 33/303 series.

It is nice to have GEC KT66 valves but Marconi and Osram are just the same having been made to exactly the same specification using exactly the same materials and were often made on the the same machinery.

Always ensure that the seller has tested the amplifiers and can vouch that they work, untested items should be treated with suspicion and bids placed accordingly.

The transformers for these are no longer available and second hand amplifiers might be suspect. Check internal images for leakage of bitumen from the transformers.

This will not mean that the transformer has failed but it will give an indication of use and because the QUAD 22 controller, and any tuners attached to it, will get their power from just one of the QUAD IIs the mains transformers can get very hot indeed.

Because a unit has had internal components replaced does not mean it has had a breakdown. It is often a sign that the owner(s) have always looked after it and kept it up to specification.

Amplifiers that are VERY rusty have often been stored in a garage and shed, these are to be avoided if possible unless bought for spares. The damp causes many more hidden problems and rectification can be very costly indeed.