I have a Cambrige Audio C500 and P500 that I am using to power a pair of M22s...I would like to add a sub to relieve the M22s from producing sub 60hz audio. Am I correct in assuming that I will have to connect the preamp to the line in on the sub and the line out on the sub to the amp for this to work? Would the crossover on the EP 175 be up to this task (is the circuitry clean enough)?

cross over at 90 not 60 lets the mains work easier and lets sub do its job

Good call, Polara!

i have mine at 80, but 90 will work, too

I certainly agree with the previous replies that it would be good to cross over your M22s and a sub at about 80-90hz both to partially relieve the M22s and to get better bass. The problem would be how to do it with your present equipment and what you propose to get. Since your Cambridge control and power amplifiers are two channel and have no sub out or bass management this isn't as simple as it would be with a multi-channel component. The question wouldn't be whether the EP 175 circuitry was clean enough, but whether it existed at all to accomplish what you want. In particular if you attempt to hook up the way you suggest, the question that arises is whether the EP175 has filtered line-level outputs and at what frequency. In the possible absence of filtered outputs it would be possible to use passive 85hz filters(about $29 a pair) between the C500 outputs and the P500 inputs and not to run the M22s through the sub. It would be helpful if someone familiar with the Axiom sub input and output provisions would reply.