Basically, the conclusion you came to while comparing the 2 preamps doesn't characterize neither tube preamps nor SS ones. There are tube preamps out there that can blow you away with the detail, imaging, dynamic drive and soundstage depth and width.
My answer is yes. It is possible.
Some tube preamps you may want to check out for the above qualities are:
ARC(older, with 6922 tubes) LS-15/16MkI, LS-25MkI, LS-5
Sonic Frontiers
Aesthetix Calypso
BAT
Blue Circle BC3000 MkII.
If you won't be impressed with what these tube preamps can do, then SS is your game.
Is it possible that a better tubed pre (such as Cary slp-98) would retain the clarity and details of the Plinius and add the midrange lushness? Or would a hybrid tube pre give the best of both worlds (like a Cary slp-308)?
My answer is yes. It is possible.
Some tube preamps you may want to check out for the above qualities are:
ARC(older, with 6922 tubes) LS-15/16MkI, LS-25MkI, LS-5
Sonic Frontiers
Aesthetix Calypso
BAT
Blue Circle BC3000 MkII.
If you won't be impressed with what these tube preamps can do, then SS is your game.