ahh sorry I thought they had made it so its able to be routed to all the dacs with the BIII in stereo mode, it depends on the dac implementation. PCM is louder or at least equal if the i2s is routed to all of the dacs.
it depends on the source too, I havent tested Amanero in this way to see if it has enough current, it may not be able to drive all the dac cells properly, but you could try sending the D1 ('Data' pin on Amanero) to all of the 8 PCM inputs (SData1, SData2, SData3 etc). so you have GND, BCK, LRCK and then send the same Amanero 'Data' connection to SData1, SData2, SData3, SData4, SData5, SData6, SData7, SData8 (its a pain, but you should really pair each with its own ground as well. is there a way to map/copy the inputs like you can the outputs? long time ESS user here, I have Buff32, Buff II, but moved on to Ackodacs before the BIII and not sure if you can access these settings
yep, check the input remapping section of the integration manual
page 27
with spdif this can be done internally so that its just copied to all the dacs internally, thus is louder. with BIII being set up with multichannel as a possibility, perhaps it doesnt do this, so you will have to do it physically.
BTW i'm not just making this up =) even just try sending to 2 of them and you should notice an increase in volume. this will give you higher DNR as well.
actually here, problem being it may mess with your DSD settings
for your BIII
1 JPCM2 Jumper 2 for PCM stereo mode, joins inputs D2 and D3
2 JPCM3 Jumper 3 for PCM stereo mode, joins inputs D3 and D4
3 JPCM1 Jumper 1 for PCM stereo mode, joins inputs D4 and D5
and then i'm gathering these are mapped across to the other 4 dac cells internally
not sure how much of this you have already done?