I have a few DIY amp projects under my belt, a scratchbuilt 300B using a Hammond OPT (JE Labs), a kit Assemblage ST-40 (an EL34 amp) and some hotrodding of classic Naim amps. In my home I alternate between the two tube amps because each has their shortcomings: bass in the 300B and midrange sweetness in the ST-40. What I miss in one I can pretty much find in the other. I listen to classical, folk and instrumental music mostly although I have recently discovered a strange compulsion for Kwaito.
I am mulling about new projects to take on and I am considering an ST70, mainly because I've been reading some good things about its OPT. If I do this, I will probably be buying the amp solely for the OPT. Likely, I'll put a new driver board in, change all the connectors, tweak the PS and probably put in a new power transformer as well.
Once this is done, how good will an ST70 be? Not good for the money, not good for a vintage amp, but good in an objective sense. An example may be the Denon DL103 cart, which to me is a really good moving coil. Its $160 price is of secondary concern to its "goodness"
Maybe what I am asking is whether or not an ST70 can be made great based on the virtues of its OPT.