Nikola, the wiring looks perfectly functional. Calvins aren't a necessity. Nice if you are driving longer cables or a tougher input load on a pre-amp but for most people they are just window dressing.
Nice to hear that Joachim rates the work I did on his building his personal reference phonostage. I don't think I've ever checked and double checked component matching values and circuit operating points quite so many times.
;-)
Kuzma Stabi/S 12", (LP12-bastard) DC motor and optical tacho psu, Benz LP, Paradise (phonostage). MB-Pro, Brooklyn dac and psu, Bruno Putzeys balanced pre, mod86p dual mono amps, Yamaha NS1000m