Stereo True-Bypass Looper

[DWBH]

How is it achieved? Through relays and stuff like that?

[frequencycentral]

You could use a 3PDT plus millenium bypass for the LED.........it's one input and two outputs right?

[DWBH]

Well, one input, one send, one return, one out - all stereo.

[flo]

That's a lot of required switching then. Use relais or CMOS switches I guess.
If the inputs and returns are buffered perhaps you do not need true-bypass switching.

[frequencycentral]

Have a look at the Tine God's 'Wicked Switches', you would  need a couple of 4016/4066.