Is it save to convert XLR to RCA?

There is no benefit going XLR to RCA. The 4V you get from balanced XLR is voided when going to RCA.
You wont damage any equip., but you wont get the benefit of balanced XLR. In your case, RCA to RCA is the right way to go.

John
JW Audio

The above answers are correct, I've done it without issue to drive a subwoofer when I didn't have an extra pair of rca out. Worked well.

The 4V refers to the DIFFERENCE between the non-inverted and inverted signals that are provided to pins 2 and 3, respectively, of the XLR connector. Each of those signals individually has a maximum amplitude of 2V. By adapting the XLR output to an RCA input, you would only be using one of those signals (the non-inverted one), so the RCA input would see a maximum amplitude of 2V.

Something to keep in mind, however: Most XLR-to-RCA adapters, and perhaps some adapter cables, short the inverted signal on XLR pin 3 to ground (XLR pin 1). Many components won't have a problem with that, but some will (if it is done on an XLR output; it is no problem on an XLR input). Use an adapter or adapter cable that leaves pin 3 unconnected. Talk to the supplier to be sure that is what they will provide.

Another approach to consider would be to just use the RCA output, via a y-adapter that would allow you to connect it to two destinations. That should work fine as long as the total of the two cable lengths is not extremely long.

Regards,
-- Al

Thanks so much for the response, folks!!

I am fully aware I'm losing the XLR benefits by using a convertor. I just want a second output.