@EmmanuelX – There are two parts to this which are often confused (understandably!), so just to clarify:
Input processing channels (or just input channels) are the digital input channels which carry out audio processing.
If you come from an analogue background, these can be thought of as like everything after/below the gain pot.
The number of input processing channels is determined by the mixer, which in the case of the SQ is the XCVI core that has 48 input processing channels available.
These input channels can be sourced/fed from either analogue (e.g. local or remote XLR) or digital (e.g. USB or Dante) input sockets.
The maximum number of input sockets in a digital system is usually more than the maximum number of input channels, because with digital patching you can easily and instantly switch sources.
You can also make use of these sockets using the Tie Lines feature, which routes any input socket to any output socket without applying any processing to the signal.
For example, the SQ-7 can have over 300 input sockets connected, but will always be a 48 channel mixer.
With Qu the maximum number of input channels is matched by the number of local input sockets, hence your comment about it being either local or remote.
Another thing to point out is that without any expanders connected to your SQ-7, you could source the first 32 input channels from the local XLR inputs and the remaining 16 from USB and therefore mix 48 input channels i.e. those 48 input channels are already there.
So in short, using expanders or option cards increases the number of available input/output sockets in the system, but does not affect the capabilities or input channel count of the mixer.
The SLink connections document ( https://www.allen-heath.com/media/SLinkConnections_V1_5_0.pdf ) may also help, just note that all numbers are referring to the amount of input/output sockets and not channels!
Cheers,
Keith.
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