European made components are rare in the US. I recently restored two small, presumably late '60s integrated amplifiers. Their construction is significantly different from Japanese components, but of high quality.
The first is a Dual CV 40:
Dual is very well known in the US for turntables, but I have never seen a Dual amplifier other than this one. I am not sure Dual actually was the manufacturer, and wonder if this is a actually a relabeled Braun. The CV 40 is presumed to be about 20 watts per side.
Here is a view of the innards:
This is a very simple amplifier, but built with very high quality components. Caps were for the most part axials of values not commonly used today. I left intact the very nice power supply cap bolted horizontally to the inner frame. I replaced each of the main filters just behind the heat sinks and strapped them with a Russian made polystyrene cap as a bit of a tweak.
Note: the Dual's potentiometers at the top of the photo above are of very high quality with cast frames.
Next is the Philips 520 amplifier, with marvelous pair of round meters at the left of the unit:
Balance, bass and treble are sliders at the middle of the unit. Here is the amp with the top off:
This amp was roughly as simple as the Dual, but with a nice helping of film capacitors, in yellow above. I replaced and beefed up the main filter capacitors at the left of the photo above. The phono section is at the right of the board. The modest number of Philips electrolytic caps replaced were kind of cute:
Both amplifers sounded great after restoration, despite, or perhaps because of, very simple contruction. Solid state gear manufactured in the 1960s typically has a poor sonic reputation, but these ended up as smoothly musical with a nice helping of slam. It is not clear to me that this early gear truly sounded bad when new, nor does this seem reasonable for all cases. It is not surprising that early designs were relatively unsophisticated. However, unsophisticated is not necessarily bad. The audiophile beloved Advent 300 is a simple design that sounds great. Proper evaluation of vintage gear needs to be done with restored units. An amplifier with 40 year old capacitors will not sound nearly as good as when new.
On the other hand, it should also be pointed out that the replacement of aging capacitors with new can never exactly reproduce the original circumstances of manufacture. Modern caps have tighter tolerances, lower ESR, and in many instances cannot be found in the same voltages as the original caps. For example, Panasonic FCs of 10 mfds or less are available in 50 volts or more where lower voltages might have been used in a vintage component. To complicate matters, I tend to use higher voltage caps in general, especially in power supplies. And beyond that I often increase the capacitance value itself in power supplies. Typically, restored power supplies have a better foundation than as manufactured. Occasionally I add a tweak as described above, sonic value unknown.
The build quality in 40 year old components tends to be much higher than that found in contemporary consumer audio gear. I am of the opinion that the conventional wisdom that early solid state components are not worth restoring is often incorrect, and that these vintage units need to be restored before rendering judgment. Both the Philips 520 and Dual CV 40 amplifiers are worthy restoration candidates.