From past work experience I realised that even the most robust circuit designs often fail outside the laboratory caused by so many factors: temperature, moisture, dust, foreign obbjects... they all call really screw things up inside a product. I'll give you an example: Heat generates air current flows which draws in dust and don't forget gravity of course. The dust lands on electrical parts, which has static, will then hang on to the components and over time this layer of dust gets thicker and stickier... which causes more heat to gather... See the cycle? Then of course moisture can get in and start corroding electrically charged parts... All thses nasties accumulate over time and not many products escapes the ultimmate price!
When designing the Campion we wanted this baby to last so we gave it a few tricks to achieve longivity: Quality component choice, correctly temp. rated parts, and protect it with the most stable enviroment possible. For this reason, the Campion and all other Sonneteer products, is inside nearly sealed case. No grills, vents, slots whatsoever. Then to make sure the internal enviroment remains constant, so that the unit performs constantly too, we gave it some low efficiency but oversized heat sinks which also formed part of the entire chassis. What this does is to give it sufficient cooling with excellent temperature stability because a high mass low efficiency heat sink is far more stable to ambient temperature changes than a low mass high efficiency heat sink, so the unuit performs consistantly.
Anyway, enough talking! Just take a look inside Bernie's Campion which has been in use almost every day and has never been serviced for 13 years! The shine is still there as if we built it 10 minutes ago with hardly a spec of dust on it! We have checked its calibration and being in such stable enviroment, the drift recorded hardly warranted a tweak but we are fastidious like that... To be honest the drift was probably because the mains voltage drift from where we first made them!
I'm glad that Bernie wanted to upgraded the Campion with an internal phonostage, otherwise I would feel bad charging for such an easy service!