Y connector to use a sub

Can anyone tell me where I can find a high quality Y connector to split the signal frommy preamp to my sub and power amp?

Best Buy sells Monster Cable cables & connections.
I hate to say it but, ughh.... crutchfield sells a solid brass Y adapter very reasonably priced.
Any suggestions on a better way to hook up a sub. I am planning on running a Soliloquy S10 subwoofer with a pair of Magneplaner MG10.1 speakers. I have a Goldmund SRA for the Maggies and the sub is self powered.
Try AudioAdvisor.com as a source of the Monster splitters