concerned about using GK5 & GKC-DA to run older Roland / Boss units?

[Headless68]

....don't be - tried ( GK-5> GKC-DA)  with the VG99, left the selection on the 99 as 'GK3', set the level adjustments as normal - no difference at all to going straight in. So, any worries about the AD > DA > AD > DA conversion messing things up are not a problem
could be placebo effect, but if anything I slightly preferred something about the GK5, kind of like how I prefer the old GK2 over the 2a and GK3