The Black Hole device gains due to not being in the signal path; it also loses due to not being in the signal path. In other words, it doesn't potentially add to the amount of processing and diminish the signal further, but it also cannot impose a change upon the signal to improve it. It is perhaps the opposite of the QOL or X-DREI in that it suffers none of the drawbacks of these other devices, but cannot confer the same potential benefit as these others.
We come down to the simple truth that the best way to alter the sound is with the signal path, but it's also the best way to screw it up. Hence, there are many good designers but fewer superb designers; many good system builders but fewer superb system builders.
I can't comment on the Black Hole device as I have not heard it, but the principle is surely worth consideration. The Legacy Whisper DSW (reviewed) which I use has a rear facing driver which operates out of phase for similar purposes, to physically treat the bass wave interaction with the head wall. There is an obvious benefit to be gained in the opinion of some speaker designers/users with such a system, and it does not impact the signal of the mains. However, for many devices which are out of the signal path I find their effectiveness is an order of magnitude less helpful. I would much rather spend my time trying devices like QOL or X-DREI than work with objects outside the signal path.
Regarding power; I have found that power supplies are critical when it comes to component design. However, many power filters/conditioners are also subtractive/additive, as they harm the signal as well by being in the signal path.
Obviously, it's not recommended that you go without a power protection device like a power bar. You do so at your own risk.
We come down to the simple truth that the best way to alter the sound is with the signal path, but it's also the best way to screw it up. Hence, there are many good designers but fewer superb designers; many good system builders but fewer superb system builders.
I can't comment on the Black Hole device as I have not heard it, but the principle is surely worth consideration. The Legacy Whisper DSW (reviewed) which I use has a rear facing driver which operates out of phase for similar purposes, to physically treat the bass wave interaction with the head wall. There is an obvious benefit to be gained in the opinion of some speaker designers/users with such a system, and it does not impact the signal of the mains. However, for many devices which are out of the signal path I find their effectiveness is an order of magnitude less helpful. I would much rather spend my time trying devices like QOL or X-DREI than work with objects outside the signal path.
Regarding power; I have found that power supplies are critical when it comes to component design. However, many power filters/conditioners are also subtractive/additive, as they harm the signal as well by being in the signal path.
Obviously, it's not recommended that you go without a power protection device like a power bar. You do so at your own risk.