It is also OK to use both RCA and XLR outputs simultaneously. You will not hurt anything.
The issue with using both at the same time is that it unbalances the XLR output. This does not hurt anything, but removes the ability of the balanced output to reject common mode noise. In the vast majority of circumstances there is insufficient common mode noise for this to be any issue whatsoever.
Has anyone used the: Purist Audio Design XLR solid splitter?
Elk, are you saying that if I use XLR to my main amps and RCA for the subs, I am removing the balanced aspect of the XLR to main amps?
Go over to Dagogo and search Y splitter or Y adapter, he did a Y cable comparison and the PAD Y adapter was included.
Exactly.
But this is absolutely nothing to worry about.
I used GLS audio XLR Y patch connectors. Less than a foot long end to end. On the analog outs of my BHK pre amp for balanced interconnects to the M700s mono SS amps that have the RELS connected back ground music. And the other side is interconnected to the BHK 250 for that exceptional sound stage and depth for sensational listening. I have not done any comparisons with different Y XLR interconnects. But these where reasonably priced at $100 for four. And do the job for me.
But ideally Iâd be better off with a well built XLR splitter?
Since i have added the BHk pre amp i havenât pursued hifi improvements in cables. Just stayed with XLR over RCA. But i should do an A/B test as I do have an expensive XLR interconnect between the Dac Jr and BHK pre amp. The sparkle of the pre amp has negated any minute imorovements I may find with interconnects. Would be different if i could try cables out before purchasing. Like you lucky dogs in the USA. Ah the problems of a two tier country 
I understand that using both rca and xlr together will not hurt the unit. But since it unbalances the output would that eliminate the sonic benefit of the balance circuit. So would we not be better off with a well build xlr Y cable?
Unbalancing the DS output transformerâs not a good idea from a number of standpoints but much depends on how much your unbalancing is. For example, if the single-ended input has very high input impedance relative to the balanced device then the impact would likely be minimal.
At the end of the day, itâs preferable to use balanced and balanced with a splitter.
Paul, I assume that this is also true with the BHK preamp outputs?
Yes, a XLR Y-cable or splitter would be better.
No, it is not. The BHK has a MOSFET low impedance output stage that doesnât care if the loads are unbalanced (as long as weâre not talking radical extremes).
Awesome. Thank you Paul.