TOPIC:

Is there any issue using a 2x4HD behind an SHD? My issue is that I use a preamp in between the SHD and the 2x4HD for the theater bypass ability. I have time and gain aligned the subs as well as created a room curve in the 2x4HD. Currently the SHD is digital out to the preamp and the 2x4HD receives the sub out from the preamp. This is working great for having balanced subs when listening in preamp 2 channel, or prepro 5.1.4. I’m wondering if DIRAC can still work in this setup since it won’t have direct access to the subs but instead will send a corrected stereo signal to the preamp. Ideally, I need a 3x4 solution with DIRAC 2 channel but this is what I landed on. I need to be able to listen to the SHD/preamp for stereo listening with the subs getting a crossovered L/R mono, but also allow the subs to act as an LFE in theater mode when the preamp is bypassed.

Looks like an 88A would be the better option behind both the preamp and the prepro, but they’re out of stock.

So you have a SHD, a preamp, and an AVR/AVP - to switch mains/subs between 2ch and HT duties?  Seems complicated, and bypasses the excellent DAC's inside the SHD when using digital out to the preamp.
Also, on modern AVR/AVP's there is no "LFE" out.  LFE (along with low passed speaker bass management), are both output to "SUB" out.

I just run three external switches for R/L/SUB (same thing a HT bypass preamp switch does for you, only much cheaper and without any additional signal degradation/processing):
1) Run R/L/SUB outs from SHD and AVR as inputs to external switch
2) Run R/L out from external switch to mains amp/speakers
3) Run SUB out from external switch to miniDSP input
4) Run miniDSP output(s) to sub amp(s)/sub(s) (miniDSP of course used for sub optimization to the room)

Now you have two completely separate 2ch and HT setups (only sharing R/L amps/speakers and the subs/amps).  You can use DIRAC from the SHD for 2ch, and whatever your AVR supports for "room correction" on the HT side.
 

That's not a bad idea. I'm not sure if the DAC in the SHD is better than the DAC in my Parasound P6. I could also do SHD->XLR->P6->2x4HD->Subs and P6->L/R. The BM is handled with the 2x4HD (which is already setup) and DIRAC could be done with the SHD and then analog to the preamp via L/R XLR. I know it's not ideal, but with the preamp HT bypass, there is literally 0 processing. It's the same as a switch. What I really need is an 88A downstream of everything since I have two very good DACs even without the SHD. If I could get one, I would sell the SHD or try to use it somewhere else. L/R/Subs would go preamp->88A and Center and Rears would go strait from the AVR to the 88A. The 88A would then feed all the amps directly.