@Lugia - thank you for the suggestions. At this stage I want to experiment with guitar as an input source, but am not sure how much I am going to really want to do that. My primary input is MIDI via external controller at this point. If I end up really getting into guitar synthesis I will definitely check out higher quality preamps. At this time, the 1U buff mult is the only mult on my board, so I am reticent to remove it. I intend to add a 2HP mult to each of the main rows as well, but those are lower priority right now. The 1U row is a utility row for me -- saves taking up 3U space. I might get rid of the Steppy depending on what sequencing route I end up going down. The USB jack tile is very important to me because it allows me to power my MIDI controllers without worrying about yet another brick.
@AcgNrg - good advice and suggestions; as above it will depend on how deep I end up going down the guitar synthesis path.
@JimHowell1970 - yes, I have had the ADDAC floor control utility module on my 'planned' board for a while.
I really appreciate everyone's advice and suggestions! Modular is proving to be fascinating as well as frustrating, and this community is really helpful.