Some very nice units to choose from on the list. I have owned the HK 725/770, PM655, HK775 monoblocks, Citation Eleven, and Citation A. After lusting for a Citation Sixteen for several years, I finally found one locally and have it running in my main system driving a set of Dahlquist DQM-9 as secondary speakers. The Sixteen is connected to a McIntosh C46, though it would pair nicely with either the Citation Eleven or Citation A. The 775s really lacked nothing, but the Sixteen brings even more.
The Sixteen is a robust power amp, and I had it on my radar over the Nineteen because a)more powerful b)protection circuitry for the outputs c)looks much better to me (black /silver with heavy duty handles and unique angled meters). Both the Eleven and Seventeen preamps are similar in design and sound great, but the true performer is the Citation A, which was developed by Stuart Hegeman and his team of engineers as a SS alternativeto the Citation 1. They are much rarer however; along with the associated unfamiliarity of the circuitry, compared to the Citation tube pres, the 1&4.
So which system? I'd go for a Citation Sixteen paired with the Eleven or Seventeen, but if you want to go with a more modest system, a 655/665 integrated amp is plenty sufficient in quality, plus it has MC input and adjustable phono capacitance. You just have to deal with those sometimes noisy push-button switches.