Don Classics NV73 alternate part help needed

Hi All, I have a NV73 kit from Don Classics on the way. There were a few parts from mouser that are on back order and looking for another supplier.

Can someone let me know which darlington transistor TIP120 (from ST Micro) alternate would be best or a source for ordering (in US). Is this a part that will have an effect on the sound quality or any equiv part will do?

Thanks!

Also the part number in the bom is Q1d. I'm not able to locate this anywhere in the schem. Anyone can shed some light on this?

This was discussed in the help thread for that project
https://groupdiy.com/index.php?topic=36831.700
Better to post in that thread instead of starting a new one.

I didn't check the datasheets but I would suspect the TIP120G would work fine.  Just compare the pinouts and power ratings on the datasheets.

The parts in red on the BOM are only needed if you are using a regular 500 series rack and need a DC to DC converter to get 24v
The schematic  doesn't seem to have the DC-DC small pcb circuit on it (the manual shows the DC-DC board on  page 12).
And no - it is a DC to DC converter so it won't have an 'effect' on sound quality per se
It is necessary if you don't have 24v in your rack. If you have a 51x rack w/ 24v then you don't need the DC-DC converter - which most would consider 'better' since the DC-DC could introduce high frequency noise or other problems into the circuit, but nobody has found that to be a problem as far as I know.