the c45 is a 2 chanell pre-amp. the mx135 is a home theater pre-amp. i think it's a 5.1. i only listen to music so i was looking for a pre-amp tuner to match my mc602 power amp. the only one's i found were the older models which were not the current style mcintosh units. i found a mx132 which is a home theater pre-amp. it has the tuner module. it's list price was 7k. the mx135 had a higher list price. from mx120 up to mx136 the 132 i find is the cheapest on ebay. i don't know why. some features that the 132 does'nt have is a balance control and a phono input which i don't really need. i think any mcintosh unit has value. they are built to last a lifetime. if you want home theater you should buy the 135 because you can also use it as a 2 chanell setup.