Splitting 1 RCA or XLR Signal Into 3....Possible?

I succumbed to temptation and purchased a third pair of Tact/Lyngdorf W210 sub-woofers to go with my Avantgarde Trios. The two pairs I currently own are wired in parallel to Marantz monoblock amps, which are in turn connected to my Tact 2.2. XP preamp. The amps see a load of 4 ohms when wired in this fashion..and they are quite happy. However..I have no idea if they can handle a THIRD pair wired in parallel...I think the load would drop below 4 ohms in that case and not too sure if the amps will like that. I think I have two options...purchase a pair of 3 channel amps and somehow split the Tact's signal into 3 (balanced or RCA cables)...or get amps that can handle a lower load and stay with the parallel wiring. I have NO idea if either of these is gonna work...so looking for suggestions/advice on what and how to do this...I suppose I could wire one pair of subs in series to the other two pairs , but no idea if this will work....ideas? I will need to find someone to make up some custom cables for me in either case....unless I can find a pro audio splitter that works (have seen some 1 to 3 XLR splitters for microphones..but I suspect they wont work...)