Where to start :) I am excited thinking about them :p You got 2 totally cool pieces of classic vintage gear there in the C2 and the Marantz. I have a C2 preamp myself (gathering dust but wont sell it cos its
excellent) and the marantz would be totally cool to have(but then I am
a little biased towards 70's vintage marantz). They ruled the roost in
HiFi amps throughout that decade.
Because they are both integrated amps, you could use them as standalone systems with a pair of speakers, and just plug your favourite gear into them. If you just wanted to run up a nice sounding HiFi, I would sell the kenwood gear and just keep the Marantz. The Kenwood kr1100 has the edge in power, so if it is grunt you are looking for use that. Because vintage sound is all about stereo, you only really need an integrated amp to get great results.
the specs are# Kenwood Model Eleven G (KR-11000G) Receiver
120W per channel
min RMS, both channels driven, at 8 ohms from 20 to 20.000 Hz with no more than 0.03% total harmonic distortion.
Dynamic power output
440W at 4 ohms
5 Hz to 70.000 HZ
5 Hz to 100.000 HZ -1.5dB
Signal to noise ratio
The marantz is a little lower in power at 75rms a channel, but will have the sonic edge in vintage sound over the kr1100. Look them up on ebay and you will find that they do have some value to collectors and people seeking nice tone. There is an 1152 for sale here
Best bet is to fire up the 2 integrated amps,and see how they are going. Run them for several hours to be sure there is no strange noises and crackles. Then decide if you want power or finesse.
You could also run both amps from the C2 preamp by connecting to the Amp in connections to the rear of the integrated amps.
happy to talk to you more about it, hit me with a Fixya if my advice was helpful to you. I would keep the marantz, use that and sell the rest and buy some nice speakers:)