Series? Parallel? Resulting impedance blowing one of the modules? Or frying the cans.
I think you should be able to daisychain them using the aux inputs. My DTX700 let’s you choose which outputs the aux input is sent to, headphone output is certainly possible.
Seeing as all 4 modules are the same I don’t think you’ll kill anything with a splitter (or actually a merger). No worries about impedance differences etc.
Hah, that’s pretty insane .
Looks good though, how did you mount those 4 modules so nicely?
this is the way I would go about it (what you wrote above). I would be very cautious connecting multiple amps together as each amp will back feed all the others connected if you used a series of cables to connect them all together. The only time ever have used Wye cables were back in the 80s when I had limited channels on the board left when recording. The Wye was used on the tom mics to save tracks. The tom mics were all dynamic mics.
read this, even though it is a little different:
The summing box schematics are for line levels, not headphone levels. T think you got that, but just in case…
Things may also change depending on the amount of channels you are going to sum. I don’t know for certain, but it is something I would check. Do a search on diyaudio.com (i think that’s the site) for diy summing boxes. You may find an instructable totally suited for what you want to do.
Line levels are the same as headphone levels. Actually line levels will can go up to ±15V, which is 30V peak to peak. Headphones never go that high.
Problem with splitting is the drive ability of the amp.
To get four signals into one headphones you need to mix them together. Device that does that is called mixer.
You cannot just connect outputs together, because for outputs this will be just like shortcircuiting them. You need to feed signal through resistors first, and then connect them together - this is called passive mixing. But for 4 channels your signal will drop 24 dB, so you will need to follow your passive mixer with active stage to boost gain and then with headphone amp to provide enough current to drive headphones.
Just get a simple inexpensive mixer Behringer, Mackie, Soundcraft, Allen & Heath, etc. all make 4 - 10 channel units. I bought a Soundcraft Compact 4 years ago, (one of the best investments I ever made) and it’s still in use as a DI, Turntable preamp with integrated RIAA EQ (for digitizing my vinyl) synth mixer, mic mixer, headphone controller for artist, etc. even though I also have a large format mixer (24.4.2), this little beauty remains one of my main workhorses.