Hello Richard,
Tube preamp idea is a good move. You may or may not prefer it but it’s worth the effort to listen to one in your system. You have the right attitude. Keep in mine that amongst tube preamps each will sound different from oneanother. Here’s what I mean, CJ, ARC,VAC or Atma-Sphere(all are well respected) for an example have their own distinct sound character. So many variables in High End audio= fun and discovery.
Charles,