I have received the message below verbatim from Cary today when inquiring about the upgrade gain, the pots, and any difference between balanced and RCA sound quality. Note an earlier post on this thread said the pots were "cheap Honeywell pots".
The gain is reduced by 6db for both XLR and RCA.
The volume pot is an Alps motorized pot custom made for us by Alps in Japan. The balance pots are made by Bourns. Both brands are highly regarded and make excellent components. These are not inexpensive components.
I think differences in sound quality between RCA and balanced could result from several factors – cables, length of cable runs, etc. Inherently, I think both are excellent
The SLP-05 is one of the most highly regarded preamps on the market. It has been around for many years. This doesn’t happen by accident

