Is age bad for solid state amps?

Nelson Pass re: the Pass Aleph O's:"...The amplifier does not need any maintenance. While the design in conservative, this is a hard running amplifier, as single ended Class A is the lease efficient operating mode. In fifteen years the electrolytic power supply capacitors will get old. Depending on usage, you will begin to have semi-conductor and other failures between 10 and 50 years after date of manufacture. Later, the sun will cool to a white dwarf, and after that the universe will experience heat death..."

I think it's fair to say that the Audio Research amp your considering will not be as "hard running" as Nelson's single ended Class A design.

"Is so complex all this"
It really isn't - you'll expire long time before transistors.

Once again Kijanki makes a good post. While most anything can ultimately fail, all but the very first transistors introduced many decades ago, have proven themsleves to be extremely sturdy devices.

While they tend to be reliable, output transistors can and do fail. The following is a useful summary of the issues (note: the British term for "tube" is "valve"):

"Transistors also have their fair share of problems, and there are some things that they are just not very good at. Some of the major failings include:

* Low Impedance - Bipolar transistors are inherently low impedance, and additional circuitry is needed to make them work satisfactorily in high impedance circuitry. Noise is also a problem when high impedance sources are used.
* Heat - Transistors dislike heat, and if it is not removed, they will destroy themselves. Most transistors can operate with junction temperatures up to about 125 degrees C, but at that temperature, can do no work at all. The life of a transistor is severely shortened by operating at high temperatures.
* Thermal Stability - Transistors are subject to some major changes in operation, depending on their temperature. This can make the design of high quality amplifiers difficult, because the transistor has a tendency towards "thermal runaway". This means that as the device gets hotter, it will draw more current, which makes it get hotter still. This continues until the maximum operating temperature is exceeded, and the transistor(s) fail.
* Second Breakdown - This is a version of thermal runaway, but at a molecular level. Parts of the internal structure become hotter than others, causing the hottest part to do the most work. This makes it hotter still until the transistor fails. Second breakdown is the most common cause of output transistor failure in power amps. It also happens very fast, and without warning - transistors can fail from second breakdown even when at ambient temperature.
* Short-term Overload - Largely due to second breakdown effects, transistors do not tolerate short term overloads, and in many cases even a momentary short circuit will cause instantaneous failure. Compared to valves, transistor circuits are much less capable with difficult loads, and usually must be over-engineered to sometimes extreme levels to prevent failures.
* Hard Overload - when a transistor amp goes into overload, it does so with startling clarity. The harmonics produced are such that tweeters can be destroyed very easily, and the sound is altogether unpleasant

Again, there are many advantages as well. Transistor amplifiers are very reliable, and can be counted on to give many years of life without requiring even a basic service (most of the time anyway)."

Source: http://sound.westhost.com/amp-basics2.htm