What's your typical routine with the soaps/creams you've been using?
Most soaps and creams can create a good lather in any water with right technique and a little work.
My water is around 210ppm, and I can get a great lather out of MdC, Colonel Conk, and AoS creams. A lot of times our technique in lathering may hinder our lather more than out water.
I've been bouncing around with the VDH line of soaps. Around three weeks ago I began combining the VDH Luxury Scented with ToBS Sandalwood cream. About a week into the combination the lather volume seemed to explode and the only difference I've noticed is that I seem to be whipping the lather longer. I got some Proraso Sandalwood Soap and used it this morning without mixing in any cream and the lather volume seemed only okay although I did manage to get three passes out of it.
Typically, I soak the brush while I'm showering, shake the water out, load the brush with soap and then lather in a bowl with a dollop of the cream and one drop of glycerine. Lately, I've been shaking less water out of the brush and that may be making a difference also.
I see that you've discovered Superlather. I also have very hard water, and I've discovered that Cella is the best soap for my conditions. It mixes very well with any of the TOBS creams that I have tried, with Spencer & Devon creams, and with Speick cream. Besides, it smells very good by itself.