Different tubes have a basic signature sound, EL34, 84, KT 88, 6550, 6SN7, etc. You can characterize the sound of tubes versus SS but there are some manufacturers who have designed tube components to be faster, more dynamic, etc. The 6H tube comes to mind for me. That being said, go hear an old Eico with the EL84 tube and hear what a fluid mid-range really sounds like. I recently heard a modified Dynaco ST-70 and it was wonderful sounding. No SS amp that I have ever heard can do what these tube amps can do. I have an old Lafayette KY-550 and it is an outstanding sound amp in stock form. The closest I have heard to a tube amp that is not a tube amp is the Gilmore stereo power amp. Not as 3D sounding but very musical in the mids.
Happy Listening.
Happy Listening.