I know this chain is a bit old, but I think the same thing just started happening with my A90. Static in the right channel from all headphone outs (both balanced outs and single ended out). It seems to be certain frequencies or volume levels that are effected (e.g., I'll head the same "static" noise on each drum hit).
Tried different headphones, different cables, different outputs from the computer (USB and optical to the D90, then XLR to the A90). The RCA outs on the A90 to my speakers do not have the same issue.
Tried different headphones, different cables, different outputs from the computer (USB and optical to the D90, then XLR to the A90). The RCA outs on the A90 to my speakers do not have the same issue.