I needed to run two amps at the same time, while I was recording. So, I was in hunt of nice ABY switch and this came up.
Pro: It has every features proper ABY switch should have. Built like tank, has enough LEDs so you know where your signal goes. On output [B], ground lift and isolation transformer to eliminate ground hums and buzz, can reverse polarity to prevent phase problem between two amps. Very effective and thoughtful.
Con: There's noticeable tone shifting when you engage 'Isolation transformer' on. So you had to tweak amp's knobs on output B again to get the sound you like.
If you are looking for proper ABY switch, look no further. Get this. I am giving just 4 stars because after recording, I hardly use it in actual gig or practice situations.