Question

I have an RM 32ai and want to potentially use it as a stagebox so i have 32 channels for back of house for only instruments, maybe use a NSB 8 for microphones and , have it all go to the back of house with a new series 3 mixer.  I don't know if the RM 32 and the series 3 mixers are compatible though.

Answer 1

No, they are not compatible with each other.

Answer 2

No, the AI and Series III families of products are not compatible, because they use different AVB protocols (AVB I and AVB II). The idea is nice, but you simply can't use a RM32AI as "stagebox" or monitor mixer.

The Series III mixers can not be cascaded and there is no possibility to expand the number of mixer channels. There is a 16 channel mixer (16R), there are the 32-channel mixers (32S, 32SX, 32SC, 32, 24, 16, 32R, 24R)  and there is a 64-channel mixer (64S). If 32 input channels are not enough, you would need to get the 64S with stageboxes or a combination of rack mixers and stageboxes.