This is somewhat covered by Doepfer's A138x: http://www.doepfer.de/a138x.htm
Yes, there are times I wish there was one more mixer input pot rather than a overall level pot.
--- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure that out)" wrote:
>
> Got a question for the group, please give me input.
>
> One thing that's pestered me about most Eurorack line mixers is they
> have this overall output level pot which I feel is at best an option,
> at most a redundancy, if nothing else another pot you need to deal
> with along with the level pots - and they all omit something tey could
> slap in the same space as the output level pot that I feel would be
> much more useful: a fifth buss input to stack mixers together so you
> don't have to take one of the input channels to do it?
>
> Do you guys see a need for a mixer that is stackable at the risk of
> removing the output level pot?
>