With your current selection of components, I also think a high quality integrated is your best move. Makes like Creek, Musical Fidelity or Arcam. Many can be found on the used market. Don't confuse these with mass consumer integrateds, these units have balls.
After that you can think about a loudspeaker upgrade and then later a poweramp using the integrated as a pre-amp. .
After that you can think about a loudspeaker upgrade and then later a poweramp using the integrated as a pre-amp. .