Thank you Dave,

There is indeed a compress/expand switch on the back of the tuner
(Cambridge Audio Azur 640T. At least, I think that's what it is; the
manual is very vague about what it actually does describing it as
"warm/lively". It does not have a very powerful effect, certainly not
enough for what I need.

I can't get decent FM reception here becuase I can't put up an outside
aerial. If I could I would be using FM rather than DAB.

Thank you Tom Sayer for the offer of an expensive compressor. but I
was hoping for something that was cheaper than the rest of the
equipment I am using.

I listen on a pair of 1970s KEY Concertos, BTW, driven by an Azur 640A.

Robert