RCA splitter

Splitters and Y-connectors are fine. I'd defy anyone to tell when one is in use.

Thing I've noticed when trying splitters is it seems to not only split the signal but also split the strength of the output, something I've noticed on many pre-amps which have two outputs. FWIW

Thanks for your responses. I'm going to give these a try https://silversonic.com/products/connectors/y-block-connector/ as they output in two different directions which will facilitate non parallel cable routing which I believe is desirable. 

Balanced splitter, gives you locking connectors, and you choose your lengths for positioning.

https://emotiva.com/products/xbal-1x2?utm_source=google&utm_medium=cpc&utm_campaign=20042245837&utm_content=656394514266&utm_keyword=&gclid=Cj0KCQjwldKmBhCCARIsAP-0rfzAVygLkxXOubiyMyRdSxJH_tWDWfjeHkAq3ELkWv88fJgsd0va648aArnpEALw_wcB

Your chosen splitter, consider supporting the weight of the two cables to minimize downward force on the male end into the units female jack.

you can make your own to use locking connector to hold the weight and avoid possible poor connection

https://www.amazon.com/Parts-Express-Locking-Connector-Solder/dp/B0002KR26I

@santani 

Exactly what are you trying to do? Normally, when you are "biamping" you connect the outputs of your preamp to an active crossover which splits the signal in two at the selected frequency leading to two 2 channel outputs, hi and low frequency.