C1 and C11 are almost the same, minor changes internally. The C11 is black with white lettering and the C1 is grey with off white lettering, very difficult for me to make out the lettering. The most used functions are easily remembered though.
I'm a bit of a Carver pig, two C11's and a backup C1. And that's just my preamps.
For anyone doing the BillD mods and changing out the RCA jacks for nicer gold plated ones, I'm the guy that sells the aluminum back panel plates mentioned on the Carver Site. It's a nice upgrade.
BillWojo