I think either a Y adapter or a dual output block available from AudioQuest is your best answer. Unless you have XLR then the Y is all there that I know of.
How to hook up 2 amps from one set of pre outs?
I have a Simaudio I-5 (70W X 2) which is not quite powerful enough to truly push my (Inefficient yet wonderful) Egglestonworks Fontaine's. I am considering adding a slightly older Celeste SimAudio 4150se into my system (150W X 2, versus 70W X 2). Should be enough power. I have a TBI VI powered sub which is currently being fed it's signal from Pre Outs on I-5. How do I connect the 4150se from Pre Outs and my TBI sub at the same time? Can I use a Y Connector on PreOut's? Or is this a no no.