One DAC to Rule it All

@rhg3 finally found me. Here I am in all my glory.

OK. @koestner the problem is you need a DAC channel in front of every amplifier channel, in your case we are dealing with 4 channels, two subwoofer and two main. The dBx has 6 DAC channels in it. Any additional channels are not required. It is really a small professional PA system unit with features like feedback suppression for microphones. 

Between you me and the woodwork the DACs in the dBx are not so hot. The improvement of a digital two way crossover in managing subwoofers can not be overstated, however I think you need to head in a more streamlined direction. I spoke with the folks at Benchmark recently and they are extremely cost conscious. What they are doing is using a MiniDSP SHD Studio and two of their stereo DACs. They say they are getting terrific results with this. The Studio includes Dirac Live and Streaming. Even more streamlined is getting a full function digital preamp. These usually include an ADC with several analog inputs, some even have a phono stage, bass management, room control and streaming. Examples are the MiniDSP SHD and SHD Studio, Anthem STR, Trinnov Amethyst and my personal favorite the new DEQX PRE series. Prices range from $1300 for the MiniDSP to $13,000 for the DEQX PRE 8. The problem you can run into using separate digital items is they can get confused talking to each other causing jitter. You can handle that with a master clock if the equipment has a clock input. In the past each digital piece had it's own DAC and signals were passed in analog. Now we use much cleaner digital interconnections. Unfortunately that leaves the door open for clocking problems. This problem disappears when the clocking is handled by one piece.

I think you should look into the MiniDSP SHD studio. You have one DAC. Just get another one and you are in business. Should you choose to get one order it with the UMIK 2. It is a much better microphone. Any unit can only be as good as the data you give it.

What subs are you using and what is your crossover point and slope?

@koestner 

I am one of the people testing the Beta programing of the new DEQX units. My Pre 8 is due to be shipped out next week, FINALLY. The first thing that happened was COVID and they lost the supplier of the main processor they were using. They wound up redesigning the units around another, even better processor. It also required revising the programming. All this took two years. Then, a problem developed that required redesigning one of the boards and finally two out of the first 100 units built developed the same intermittent problem. They wanted to make the diagnosis before letting the other 98 units go. They are all PRE 8s by the way. Most people will require only PRE 4s. It is the identical unit without the 4 way crossover. It won't be available for at least another 6 months. So, take your time and play with the dBx. I've been doing the digital thing for almost 30 years starting with a Tact Audio 2.2X and I am still learning. 

Your subs are passives! Did you build them? I have the same situation as you, an open floor plan and passive subs in a large room. Two 15's will do a lot of damage and is enough for a point source system. 

@eddnog That is not a fair comparison. The DEQX Pre 4 is a $10,000 unit. I will have a lot more to say in a week or so as my DEQX Pre 8 will be delivered this Tuesday. 

@koestner Great solution! I had Velodyne subs way back. Eventually the surrounds fell apart. I kept one to use as a Fish Tank stand. I build my own subs now. I am working on Model 4 at this time. They are four balanced force subs with ultra low resonance enclosures using a total of eight 12" drivers. 

The plate amps in most commercial subs are cheap and the integration is awful with those silly low pass filters. Passive subs give you much more flexibility allowing you to use full two way digital crossovers and your choice of amp.

@kraftwerkturbo Excellent! I seems to be hard to convince people that raising the subwoofer crossover point to 80-100 Hz greatly improves the performance of any speaker. Yes , you use subwoofers to improve your lowest end, but 1/2 the advantage is improving the performance of the main speakers. It requires a full 2 way crossover with time alignment and slopes in the 6 to 8th order range.