Which has richer tonality, the Holland e188cc or the USA 7308?

lowrider57... Yes. Still looking for the iteration that's a marriage between the flavors I cited here, not that I'm unhappy with either. Far from it. Besides, tube rolling is a pleasant pastime during the lockdown here in Seattle.

Oh yeah, I love tube rolling. I may be as discriminating as you are.

Did you ever try the USN7308 (or 6922) Amperex offered to you?

Not from rodman99999, elsewhere. Better than my orange label USA 7308. More articulate. Deeper bass. Now if I can only find something with its clarity and spatiality and the rich tonality of the 6922...

Hi,
depends where you want to use them for, and believe that 1960-1964 are the ones to seek. USA 7308’s cannot go wrong, are nice, quiet with very good bass but a bit relaxed on top always leaving something to be desired. Holland ones sound more complete with a bit better attack and sense of flow. Between the 2, Siemens E188CC fills the space nicely with great bass and livilier top.
More effortless sound, flow and richness comes from Holland D-getter 1960, otherwise any VR5 O-getter (generally my favourite E188CC) will do. Even though Holland ones are branded as Philips Miniwatt, Amperex, Valvo, Dario, RT..i would search for Philips Miniwatt SQ or Amperex PQ with 2 stars on them (i’ve seen only 1963). And now to make things more complicated try to listen to some 6N23P (not EV) Voskhods from 1975-1976 NOS, they are fit and forget with the best flow, soundstage and presentation of detail, they do not last as long as the E188CC, can take abuse have the lowest running temperature and are cheaper. Anyway these are the ones i use in my line stage and Hollands or Siemens in my phono stage-depends where you want to use them.