If you are a looking for a pure analog only preamp, the P7 is the best. The C1/C2 are older and appear to have switching power supplies and power supply banks are not good enough. The P7 has superior linear power supply and architecture. It will not be nearly as good as Krell S1200, but it is very good for the cost!!
If you are looking for HT Processor on the cheap, there are better solutions than C1/C2. Look at the Anthem Statement D2, which are going for just over $1k. They are still older, but much better than C1/C2.
Marantz AV7702 or AV7703 are in the $1k to $1.5k range and are very good (better than the P7 because of the discrete analog circuits). If you can stretch to $2k, the Marantz AV8802a is excellent. (look on ebay for these).
Of course, none of these are as good as S1200, but in the end, you get what you pay for.