@TLS Guy : Thank you very much indeed. I am truly sorry about not having seen your question before my last posting. My excuse was that I had a waking moment last night at 5am and rushed into the lengthy screed that now looks well over-baked. I should remember always to leave a post until I had checked everything!
Anyway, now down to the nitty gritty. It is all my fault, not the amps - as you suspected when you asked if I had done it all correctly. I thought that as I had gone over all the settings twice that I must have done so correctly: clearly an arrogant mistake. I had not noticed a previous mistake in the reassignment of the Media Player input. I had accidentally assigned it to input 1 (the CBL/SAT) rather than to input 2 (Media Player).
I grovel in my arrogance and fully apologise to all. The sound is now as sweet as it used to be and I am delighted.
I would not have achieved this without the enormous help all of you have given, and I have learnt much in the process both about the electronics and of myself!
Now no more questions, at least until the next piece of equipment comes up, something which I don't hope will happen with my varied pieces of equipment from different ages.
One thing I am miffed about is why Denon allows the use of the digital coax to American customers while refusing it to those in the UK. Even the Denon engineers didn't spot that I might have a different model and didn't ask where I was based. It seems stupid to me, or perhaps they presume that in the UK nobody buys CD players any more and therefore don't put the necessary instructions in the manual Although they do say that some inputs are assignable, they don't give the full detailed instructions of the steps needed.
Thanks again for the patient help with which you have nursed me through all these steps.
Tony