Hello,
I would like to record Dry and Processed signals at once using audio outputs connected from QC to Audio Interface. Technically, it seems pretty east, route another path just after input, without any blocks directly to output.
Would this dry signal have high, studio standard quality? As tracks will be recorded at home, but then send to mixing engineer.
First thought was to buy a DI / Splitter, but does it really make sense while I can do this using 2 paths in QC?
you could do that but you’re sending it thru 2 sets of preamps and converters if you’re using an external interface. The difference may be negligible, but is there a reason you don’t want to use the QC as a USB interface? Then you get 2 DI tracks ‘for free’ without using the grid or multiple outputs
We will be recording guitars using QC and Fractal to capture our live dialed sound as well as dry to give mixing engineer more flexibility.
My home studio is setup with Steinberg interface, monitors and Cubase and Win10. So it will be inconvenient to change Cubase setup each time, reconnect devices, drivers etc. So this is the reason 
Don’t buy a DI splitter. One of my favorite QC attributes is it’s digital routing. I use this frequently, parallel signals (wet/dry), mono/stereo with split, or doubled mono. Having 4 independent lanes is a dream. They sound great and gain staging is easy, especially in tandem with studio rig.
Side note- ive had my Qc for ~1.5 yrs and never used it as an interface.