^ Bump and thanks for the efforts above.
Picked up a mk2 for pretty cheap and it's on version a3.04. Should it be changed to the older version or can you? This isn't an Oade unit.
For digital in does the level control setting Manual vs Automatic Level Control (ALC) matter? I recall reading about the mk3 and the gain knob changing levels when using the digital input. Hoping that isn't an issue with this one.
I have both the MKII and the MK III as I picked up the MKIII a while ago dirt cheap. With the MKII, when using as a bit bucket, the gain is fixed like on most bit buckets. On the MKIII, for some reason it is adjustable. I almost feel like it was done in error, but who knows. As for the firmware, I see no reason to want to downgrade your firmware.
FWIW, (which is subjective) I like the MKII better than the MK III. That seems to be where they got it right. That said, the MKIII is still very nice. I have only used both Marantz decks as bit buckets, I have never modified either and have never used them with analog in. (Mics > USB MixPre 2 > Marantz II or III, or Mics > Mytek > USB Pre2 to Marantz II or III.)