Greetings. I would be grateful for any suggestions (and apologies in
advance if I am asking a question I should already know the answer
to).

I have an 12 year old Melos pre-amp (sha-1 if memory serves). I've
left it turned on most of that time...I am wondering if I should
replace the stock tubes on general principles (age)..and if so, what
tubes I should buy. Any thoughts, again, much appreciated.

One related question please: will ageing tubes produce any (bad)
audible evidence of their decline? It seems to me that in the last few
months I have to turn the volume up more than I used to for good
listening...that could be that my hearing is changeing (sigh), or some
change in the acoustics of the room, some other component (e.g. the
tubes in my cd player burning in more), etc...but could it also be
because the pre-amp tubes (which of course nominally control volume)
are ageing?

many thanks.