It’s identical to the MK1 by design, it’s analog straight to the compressor (no gain/trim pots) - there are no differences electrically in terms of i/o either iirc so anything you see for the mk1 applies - there are possibly hotter outs on the A4 mk2 iirc which are rated in the ballpark of the AR ins (for all 4 voices firing) … A4 mk1 is sorta usable into AR mk1
Nothing is going to change this, so read up … basically use modest levels in AR voices or boost externals pre input or use hot(ter) gear etc