I don't know which Oppo you have, but direct to the poweramp/s will be the most transparent/dynamic sound you will get, if the Oppo you have has it's analogue volume control before it's output buffer. Or if it has a digital domain volume control then you should use it within the top third of it's full output as not to chance "bit stripping"
If you don't like this uncoloured sound then an active preamp may give the colouration that suits you, but that's going to be a bit of a hit and miss merry go round to find a preamp that suits what your colouration preference is.
Cheers George
If you don't like this uncoloured sound then an active preamp may give the colouration that suits you, but that's going to be a bit of a hit and miss merry go round to find a preamp that suits what your colouration preference is.
Cheers George