This is an idea that has been stuck to my head for a while.
What about using a 2123H as lows in a passive 2-way vocal monitor? It woud be very small, 9liters plus drivers and port. Even the tiny SRX712M would look big and clumsy in comparision with that. The highish cutoff frequency of about 200Hz would not impose any problem since they will be at the front of the stage, close to the main subs.
However, what treble could it be mated sucessfully with? i also have a bunch of (dead) EV ST350A's laying around, would these somehow cut it? Or is there something better that is small enough to keep the total boxsize to a minimum, can accept a crossover frequency low enough to meet the 2123 and can take the beating as a vocal stage monitor for a rockband? (roughly 120dB) while also not being made of unobtanium or pure gold?
And most importantly: sound good and not being a feedbackproblem.
The microphones this "hifi" monitor would be used with are Milab LC25 and LC28 condensers. Very sweet and natural sounding mics, so it is sad to destroy the sound from them.