Worked for me. No problem at all....
the use of an active c-over would be appropriate if you wanted to use two diff amps to horizontally bi-amp AND neither one had any gain control. when I vertically bi-amped with two identical amps (of course they would have to be to vertically bi-amp) I used Y cables. The advantage of y cables over a y adapter is that you eliminate a pair of cable junctions.
I just went through a negative experience with the Y-splitters when I added a powered subwoofer to my system. I first tried a Monster Cable Y-splitter and heard, to my surprise, significant losses of depth and fine transient information. Same problem with the AudioQuest and Dayton Electronics splitters. The solution: my main amp has dual inputs, single-ended and balanced. So I use the single-ended connection uninterrupted from preamp to amp, then I use an XLR-to-RCA adapter on the balanced amp connector to daisy-chain the signal out to my subwoofer amp. IOW, the balanced amp input can also serve as an output passthrough for the preamp signal. The signal to the main amp remains unmolested.
I've used Y splitters in the past and haven't noticed adverse performance; although I didn't perform any kind of an a/b test to scrutinize it. In my current home theater I'm running vertical biamping using Eagle 4 amps that have a jumper soldered internally between the RCA inputs. So one interconnect plugged into either RCA input on the amp drives both channels. This has worked nicely and in my mind is cheaper and probably the more electrically direct than Y splitters. Of course you have to get over the fact you're modifying the amp (mine was done by the mfg).