Adeeb: In response to a couple of your comments:
- the overblown chestiness of some songs has been drastically cut down.
- echo has been reduced
- in one case, listening without the filter made it obvious that my right speaker was delayed comparing to the left. With the filter, the delay was eliminated. It was shocking.
- what comes through is less muddled
- most songs seem to lose a lot of their energy with the filter enabled
- the soundstage seems to collapse significantly and the sense of “air” suffers
- I’m not sure if the instruments sound natural – saxophones, trumpets, guitars… all sound thinner as if some of their body has been stripped away. This might be because I got used to the sound with the reverb and coloration that my cabinet adds. But I think it is more than that.
First, I have found that getting speaker distance (or delay) set up correctly down to the 1-inch level matters a lot, particularly with overall imaging. Good news is that you can set the appropriate delays in most software (HQPlayer, Roon, etc.) without further changing the sound. If you fix this first you will then be even more sensitive to the issues you mention that I respond to below.
Second, each time I have played around with REV or Dirac-based frequency adjustments, I encounter exactly what you describe (loss of energy, loss of transient bite, loss of air, instruments sound thinner). There are equipment manufacturers (Bryston being one) who don’t offer equalization/room adjustment in their equipment for just this reason. Dirac goes to great efforts to say that its software “compensates” for this by both adjusing frequency and retaining time coherence, but my experience says you can’t really do both. I think that is why fixing the room’s own response, through curtains, carpets, diffusers, absorbers, etc. is almost always a better place to start and then to resort to REV or Dirac only to fix the very last bit. Some choose to only let these programs adjust frequency response below say 200Hz so that the time coherence, transients of everything above that remain untouched.
What Magnus has created here is hugely valuable as neither the software nor the testing methodology has previously been laid out so clearly. But as we learn to use the software better, I think we will also discover some of these tradeoffs and the limitations they impose.