The Altavista Audio (AVA) link is a great resource. AVA is owned by the former President and chief designer of Counterpoint, Michael Elliott. Thanks Stevemcx.
Yes, the SA-3 and SA-5 are full function preamps, including phono stages. But the SA-6 is more accurately a mc headamp. It is used to provide additional gain for a mc cartridge before an RIAA equalizer. Therefore, a phono stage is still necessary when using the SA-6.
If you interested in learning more, search the archives for discussions of headamp and step-up transformers.