Is it OK to have xlr and rca connected at same time on arc ds450?

Based on schematics I’ve seen for other ARC designs I suspect that the signal pin of the RCA input connector for each channel of the DS450 is wired directly to one of the two signal pins on the corresponding XLR connector, very probably pin 2. And when the RCA input is being used the switch on the rear panel simply grounds the other input signal pin (pin 3) of the XLR connector, while the switch most likely does nothing when it is set to the XLR position.

Given that, at the very least sonics are likely to be adversely affected if both inputs are connected at the same time, and damage to one of the preamps is also a possibility, eventually if not sooner.

As further confirmation, I see on page 2 (pdf page 5) of the manual for the amp statements saying "disconnect any balanced cables" for single-ended operation, and vice versa.

Regards,
-- Al

No, it is NOT OK to connect both xlr and rca at the same time!
If any one of your pre-amp has HT pass-through / bypass, you can plug the other pre-amp into it. 

That's a shame- I was really hoping that I wouldn't have to connect and disconnect cables each time. These high end items don't take well to any sort of wear and tear...
Thanks for your advice! 

that's a fair point you make about the xlr's being durable. i'll just have to be careful (as always) when plugging/unplugging the inputs each time. Maybe steering clear of heavy, rigid interconnects that put strain on the terminals is also worth doing.