MartinM:
Can now report that the sound quality is much improved, particularly in the higher frequencies which are much clearer, detailed and have a "sparkle" to them.
"much improved"????????
Are you sure? Or are you not falling for the trend of replacing capacitors for no good reason other than sound modification.
If you want the typical Far Eastern "tinkle tinkle" sound then buy a Far Eastern amplifier. If you want the American bass heavy sound then buy an American amplifier.
The typical B&O sound is smooth, mellow and easy to listen to, from brand new. I bought the first Beocenter 9000 when they arrived in the UK in 1986 and I had a new Beomaster 1900 before that. In my current situation, I have had 100 or so 9500's and 9300's and the like through my hands and I listen to them all. Their sound type/quality, call it what you will, has not changed over all those years!
The majority of those components that you changed are not being used in stressed situations, will not have deteriorated and I am convinced are still within original spec. They are being changed for changes sake and the result will be modification of the sound type away from that which was designed, rather than any real "improvement".