Good question and none of the speakers I mention have real bass down to 30 hz. I would not characterize the brands I mention as broadly European.
These have very traditional BBC school voicing. Natural midrange tone, especially with voices and acoustic instruments, at the expense of some dynamics. They would sound very different from other major European brands such as Dynaudio, Focal, B&W or Sonus Fabor. The PSB is a Canadian design made in China and is a more modern sounding speaker. It is more forward with deeper tighter and faster bass but I would not characterize it as "natural". Some American speakers are very natural like the DeVore line.
One company that tries to provide a neutral midrange but a nice open sound is the Canadian made Totem. I think they offer a very good overall package and they are widely available with a number of good sounding speakers at different price points.
BTW your Quads are excellent speakers. I have always been impressed by this company's traditional box designs and would say they too are voiced in that traditional British way.