Line in not functioning when using audio over usb

Hey I’m trying to go dawless and use the limited gear I have , I would like to use the mpc ones line ins but when I connect my mc101 via usb and use it as my main out the audio from the mpc is monitored out of the mc101 main outputs , however the line on mpc isn’t working . Is this normal or am I doing something wrong ? Basically I’m trying to do all this with the gear I have available. I have a mpc one plus , mc101 and a td3 and rd6 my plan was to use berhinger box’s as they are mono one each to the line ins then mpc via usb to mc101 please help lol

Plugging in an audio interface disables the MPC’s internal audio, meaning you can’t use both simultaneously.

if you want that many things plugged in at once you need a proper usb audio interface (or a mixer) with more channels

look at the behringer umc404hd. it's quite affordable.

See that was my main worry and thanks for answering and confirming. Ok I’ll just have big things about I might sample the td3 and do away with rd6 as mpc can do that ok . Plan b
Thanks