Using Mark Levinson No. 380 preamp output simultaneously

I have a Levinson Reference No. 32 preamp (no longer in use, loaned to a friend).  I use to use two outputs--one to the main two-channel amplifiers, the other went to an ambient sound synthesizer that fed four smaller speakers set up to the side and rear of the room.  

That is a less common use than for subwoofers.  Most linestages can accommodate two outputs--whether by having two sets of jacks or use of a splitter--and there should be no problems with significant sonic degradation.

I have a 380s.....I've used both outputs to biamp my Infinity RS-1s for 20 years or so.

You can use it but it is not ideal.  The manual urges against it.  A better solution is to use a splitter off the balanced output and an active balanced to single ended converter.

Thanks for all the help..
@willcycle why is it not ideal? I was actually  thinking  about running the balanced to my mids and highs, and use the rca for my woofers (biamp) since my amp for my woofers only has RCAs

It's not a good idea because it unbalances the balanced signal.  The single ended output is taken from the non-inverting balanced output.  If the two phases of the balanced output see different loads they are no longer balanced.