Active DI question

[FUZZZZzzzz]

Hi guys!

I've build this phantom powered DI based on a design by Elliot Sound. Unfortunately I could not figure out which schematic was used, but I build it using this layout. I works very well when I plug it into my interface. The question I have is about adding a through jack to the DI (which sends the dry signal directly through. I tried with soldering a 2nd jack to the input jack (both grnd and signal), but every time I plug both the channels into the interface the volume drops drastically. I have build a Bo Hansen DI before that doesn't have this problem. Is it because of the design? or am I doing something stupid?

(edit:or both )

[garcho]

https://sound-au.com/project35.htm

Is it Figure 3, on that ^ web page? Looks similar, minus a couple 5V1 zener diodes, but I haven't given it an inspection.

Forgot to mention, mixing signals requires resistors, if not a summing op amp stage

[Banjan73]

What about using a switch like true bypass or something?
Or perhaps there is a need of a buffer here?

[FUZZZZzzzz]

Hmmm.. I think I got it mixed up with passive DI's. It probably needs some extra components.