Balanced Y Adapters--Where to Find

The manual to the Levinson 380S pre specifically discusses the use of Balanced Y Adapters for passive biamplification. I have no clue who makes these or where to buy them. Can someone offer direction?
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Either Cardas or Purist Audio Design
I have a pair that were made by Tara Labs. Very good for use with Subs if you don't have 2 preamp outputs. It isn't uncommon, you just need to order it. The brand is more a concern about system synergy than anything else.
Transparent makes these also...
I bought a pair of Kimber KCAGs. Just remember to get the right male/female couplings on the right ends... (oops!).
To repeat what Nsgarch said - Cardas will make them for you.

I think there were some for sale here last year, but they were very short. has lots of stuff like that.
You may want something better since you're using Levinson, but I've good results from my Cobalt Cable Y's. Very cost effective. I bought a pair of these to use with my Norost SPM interconnects while I saved up for another interconnect pair for the second amp. Now I just use both amp out ports on my preamp which I think is better. I do think I get more background detail now, but I wouldn't say these Y's dimished the sound all that much. I'm sure the Purist would be even better.

Thanks everybody--I had no notion that there would be this much variety.