If you like a preamp that does not add a coloration to the sound, you will be happy with the High level input/output. And if you plan to play vinyl,
there are hundreds of Phono Preamps to choose from. At least you will know the Diana will not be adding any coloration to the added phono pre.
There are no pots to clean, All are sealed. And I wouldn't be "shot gunning" cap replacement unless there is a problem.
My Sumo Diana is totally a stocker, but did need a new four gang volumn pot. Quite a choir.
You did good on the price. This preamp will compete easy with modern ones costing 3 grand or more. One of
James Bongiorno's best.
Here some more info for ya.
www.davidsaudio.com/html/sumo_brochure_2.html
Cheers,
Jm