Additional 220 or additional sub?

[thumb5]

I remember the upgrade from 140 to 220 Pro CI being just ok. Turning that into a 440 Pro CI was jaw dropping. RCA to XLR with lifted ground was better than a digital to digital connection between them. I don’t do fancy cables, I’ve never felt it necessary try squeeze something more.

For the sake of avoiding potential confusion (not trying to pick holes in your post), I'm pretty sure the connection between the two Expert amps in a dual-mono system is always digital, whether it's configured as RCA-to-RCA or RCA-to-XLR.