Hi. You would connect the two RCA connectors on the y-splitter to the red and white RCA jacks on the back of the sub that are above the word, "INPUT".
If I find a copy of the owner's manual, I'll let you know if you can just use one of those inputs (so you wouldn't need the y-splitter). Some subs are set up to work the same regardless of whether you connect to the right input or the left input, but I don't know if yours is like that. If you have the manual, you could check to see if it discusses that.
I have the unit in question (Wharfedale Topaz SW-15). You won't find the manual online. I just picked it up from traderjohn online. I'm not sure of the manufacture date, but let me check....(Bending down to knees to tip forward and look for info on rear of sub). No manufacture date listed but I think the first run of these was back in early 2000's. There's next to nil for info online. I read the 2 page brochure.
If you have a single line level (rca connector typical) sub out from your receiver then use the left (white rca) line level input (no splitter necessary). I'm feeding another sub (jbl sub10) off of the line level output from the Wharfedale.
The few reviews I found for this line dating back to mostly the early 2000's were all over the map and mostly lacking in critical reviewing skill (never would have passed on any of these hifi forums).
I took the plunge on this. Just got it today. One of the laminate edges was damaged in shipping (very minor superficial). The pack job easily could have been much better. Not packaged nearly as well as the JBL. Still these things survive somehow.
I need to let it burn in/set it up before I can comment on the ouput...I don't have test and measurement equipment, just ears.
