Hi Janob!
Yes, I am the one who designed and builds these replacements. Thank you for your order!
Regarding the stereo relay mod by Doctor C - It would depend on how it was implemented. If they ran power directly from the power supply, then yes, those wires would have to be removed/desoldered. But you would only need to resolder them to the new power supply.
If they mod was done by jumpering a +5V line from another location and not from the power supply, you could just swap the PSUs without issue or concern.
BUT... I cannot make any guarantees since I'd have to see what's been done to your particular unit.
Feel free to post some pictures or details and we can work sort it out (or ping me directly).
-Chris