Thanks St PatGuy.
It has the same look as the earlier model, CD T100 , and is already around for more than 10 years. I did my research , find out the 4 tubes 12AU7 are quite common , and there is room for upgrade. Two are working for balance & other 2 for RCA, which I don’t use.
Just wondering if I can replace only 2 tubes I use and leave the other to age ? So far , I’ve only spent not 50 hrs to burn in. A little too early to think, will look into it when time comes.
You should be able to just replace the two 12AU7s for the output stage without changing the ones for the RCA/XLR outputs, but I can't find any information to confirm that. In any case, the tubes should last for years, and, like you found out, the 12AU7 tubes are plentiful and easy to find.
