I am not sure that generalization (16 ohms = lower amplifier distortion) would apply to every variety of solid state amplifier. Tube amplifiers as a class tend to have a much higher output impedance than do solid state amplifiers. This does give an advantage for 16 ohm speakers. What I abhor about "4-ohm" speakers is that they tend to be multi-driver arrays with very complex crossover networks. This is a set-up for low input impedance and for power-sucking crossovers. You can get a Pass or other high quality solid state amplifier to drive these beasts because they generally have an output impedance well below 0.5 ohms, and there will be some listeners who like the results. Speaking only for myself, I never have. But it is wise to think about the speaker first, and then to choose an amplifier well suited to driving it. Once that process is done, I have always tended to prefer at least modestly efficient speakers with high input impedance that can be driven by tube amplifiers (my preference has always been for OTLs) or low power Class A solid state amplifiers. Not everyone will agree, and that's fine.
Don't forget to get rid of those "rheostats", which are probably L Pads. L pads sound terrible and one is always better off without them. Replace them with discrete resistors or no resistance at all. See my earlier post.
Don't forget to get rid of those "rheostats", which are probably L Pads. L pads sound terrible and one is always better off without them. Replace them with discrete resistors or no resistance at all. See my earlier post.