Reading the help pages at Sweetwater and a few other sites, I see a Line Mixer “Live, line mixers let you combine multiple sources such as in-the-booth playback devices into a single output, freeing up channels (and preamps) on you main board.” which sounds kind of like what I'm looking for.
But by definition those take line level, meaning each instrument already went through its own DI.
Is there a combining DI that allows multiple instruments to be plugged in and delivers a mixed line level output? Especially if the inputs are from identical pickups and each has its own little gain control already.
The final goal here is to have our own instrument mics and mixing, so we're not at the mercy of the venue if it's a stage, and will have portable amp and speakers for playing e.g. outside in the park.
The size of the amateur gathering varies. I don't want a huge mixing board with 18 or so inputs, for expense and bulk, and it doesn't need that fine of control.
For this specific question, I'm considering this performance were there were 5 urhus, and the venue used 3 mics for them and ended up not having enough channels or mics available. They got some contact "pickup" microphones, so everyone has his own. I'm thinking I want to have a combiner to bring out a single Urhu Line to the mixer. When I start doing mixing as part of the troupe, I'll have one Line for each group of identical instruments. One time there might be 5 urhus, another day maybe 2 urhus and 2 or 3 pipas. The mix setup stays the same and the cluster acts as one voice.