I'm running two H9s, one in front of a guitar amp and one in the fx loop. I see that some musicians are running four. Aside from adjusting the Input and Output Gain and the MIDI controllable Input and Output converter gain, is there anything else I should consider to do to factor in these Analog to Digital, Digital to Analog conversions? Maybe it's academic because the tone sounds great to me, when I can set the gain stages properly, but I wonder, at what point would cumulative conversions degrade the sound?

Digital audio has been developed for decades. Almost all the music we are listening to is in digital format. Nowadays most albums are recorded & produced digitally. How many A/D D/A conversions are involved? I think we should trust their quality.