TOPIC:

I have a DDRC-24 managing two subs (only), and have just purchased an Integra DRX 3.4 receiver. The DDRC-24 obviously has Dirac Live - as does the DRX 3.4. The DRX 3.4 has two physical sub outputs, but only logical output - it's just Y-split inside the receiver.

I'm trying to establish if there's any point running Dirac on the DDRC in this configuration, as well as on the 3.4 - or if the "double Dirac" is redundant and I should just run it on the 3.4 (along with performing other non-Dirac calibration via the DDRC).

Essentially my intended calibration process is as follows:

1. Use REW measurements and/or a sub crawl to find the best two spots in the room for the subs to sit (from limited options, unfortunately).
2. Manually gain-match the subs (i.e. via rotary dials on the subs themselves, with each sub in the same location). The subs are two different models (until I upgrade soon, anyway), unfortunately. FWIW I'm of the general understanding this isn't strictly necessary with a DDRC in the mix as it can do all the gain control needed, but figure it's easy and can't hurt to get them approx gain-matched manually so the DDRC has less work to do / more headroom.
3. Use Multi-Sub Optimiser to do a subs-only calibration of the subs and upload this into the DDRC-24.
4. Run Dirac Live on the DDRC-24 (covering the subs only) ?
5. Run Dirac Live on the DRX 3.4 (covering all speakers including the subs via DDRC-24)

Essentially, wondering if step #4 adds any benefit, or is redundant (or harmful)? I believe it's redundant as Dirac acts on the input signal to the DDRC, not the output signal(s) - so you're effectively Dirac'ing both subs at once, same as the receiver will. But wanted to confirm.

Also, two follow-up questions depending on the answer to the above:

1. If the answer about double-Dirac is "no, redundant/harmful due to it acting on the input side", it got me thinking: I assume Dirac processing is separate per input channel? So, given I only have two subs, in this case couldn't I Y-split the sub signal on the way into the Dirac, then inside the DDRC route one of the inputs to sub one and the other input to sub two - and in the process gain the ability for the DDRC to run separate Dirac calibration on each sub?
2. Again if the double-Dirac answer is no (as well as the question about splitting the inputs above) - and hence I don't need Dirac on the DDRC - should I cross-flash the DDRC back to a 2x4HD? I'm not clear if the 2x4HD will offer anything the DDRC won't in its non-Dirac featureset.

Thanks - really appreciate any answers / input.

i don't claim to be an expert but here's my initial thoughts:

I'll let others confirm but dirac on top of Dirac is probably goibg to result in overall boosts that otherwise wouldn't have been permitted. 

Also if you run MSO (which you definitely should) then you're basically making the subs work together AS ONE to give even smooth bass across your listening position. That means MSO will cut some frequencies and boost others and change alignments to what may first seem wrong. If you then run Dirac separately on them, dirac may try to undo the good work MSO did. I.e. make each sub flat again. You wouldn't want that. 

Thanks for that - yeah, everything you're saying makes sense, even failing an absolutely definitive answer it does seem logical that double-Dirac is at best redundant.

I guess possibly my idea of using two different inputs of the DDRC-24 to separately Dirac each sub might be beneficial without MSO... but it sounds like MSO + Dirac on the combined subs (at the receiver level, along with all the other speakers) will produce better overall results.

Any thoughts/insights on whether I'm better to flash the DDRC-24 back to a 2x4HD given I don't need Dirac on it anymore? I'm unclear whether this offers any benefits (beyond ensuring I don't accidentally turn on Dirac, I guess).

I think the general concensus is that MSO does a better job than Dirac for sub integration. DLBM might be a different story but that's not available yet with minidsp.

Internal processing on DDRC-24 is 48kHz vs 2x4hd which is 96kHz though I've no idea how big a difference that makes. 

OK, thanks again for the info. Will probably flash back to 2x4HD, doesn't sound like any downside and potentially some upside.