I used the exact same tubes in both the Spirit II and III, but found the sound of the Spirit II to be a bit more lively, with a little more detail and transient attack. I was comparing both amps when using the triode mode.
The pentode mode does have more bass weight and "punch", with twice the clean power of course, but it does give up some texture, detail and ambience compared to the triode mode.
The pentode mode does have more bass weight and "punch", with twice the clean power of course, but it does give up some texture, detail and ambience compared to the triode mode.