Bonjour, bienvenue to ASR (sorry for my bad French).
You are right, analog active crossovers have some advantages over digital:
- only requires one DAC, as you pointed out.
- have negligible latency and propagation delay. The XO doesn't have to "think" about your crossover, so signal passes through it in an instant.
- analog volume control. It will not glitch and accidentally send max volume to your speakers, as you said.
- simplicity and low cost.
However, digital crossovers have many advantages over analog, FIR filters in particular:
- steep crossover slopes and unusual configurations are possible
- phase rotations can be adjusted independent of amplitude
- are extremely flexible, it is easy to create new crossover configurations in a few minutes. This is great if you love tinkering.
- it is possible to linearize every driver individually, using measurements taken of that driver
- time alignment via digital delays is possible. I use 48kHz sampling rate, so I can align down to 0.0208ms. If I used higher sampling rates, it could be even finer than this. With analog crossovers, you use all pass filters which are nowhere close in precision.
The volume control question is valid with digital. However, you can protect yourself by limiting the maximum output from your amplifier or DAC. I have never seen a digital volume control on a DAC glitch and accidentally send maximum volume to the amp, and this concern is completely absent with analog volume controls on amps. In my own system
here, every channel has its own volume trim, implemented three times. My 8 channel DAC has individual volume trim, and so do the amps. Finally I can implement volume trim via the crossover software. The maximum volume produced can be set with these volume trims, so even if the player software I am using for volume control (JRiver) glitches and sends out maximum volume, it will not damage the speakers. Only annoy the neighbours.
IMO, which solution is superior depends on your application.