I've been using Digital EQ for many years, starting the now venerable Behringer DCX2496, moving on to better pro units such as dbx driveracks, then various MiniDSP units and auto EQ systems.
Measurements clearly showed the early units added noise, and in the case of those with analog inputs so did listening unless really careful attention was paid to gain structure.
However (for me) since the MiniDSP onwards (and again paying attention to gain) noise has ceased to be an issue.
I'm sure it is measurable. But I can't hear it and the benefit of DSP EQ is so obvious that even if I could hear noise with my ear against the driver I wouldn't care.
The only noise that bugs me these days is that from poorly designed amps in active speakers.
Measurements clearly showed the early units added noise, and in the case of those with analog inputs so did listening unless really careful attention was paid to gain structure.
However (for me) since the MiniDSP onwards (and again paying attention to gain) noise has ceased to be an issue.
I'm sure it is measurable. But I can't hear it and the benefit of DSP EQ is so obvious that even if I could hear noise with my ear against the driver I wouldn't care.
The only noise that bugs me these days is that from poorly designed amps in active speakers.