Speaker Wire to RCA Connection from subwoofer to studio monitors is very quiet.

[justinliow]

Connecting my subwoofer to my studio monitors is very quiet.

I just bought this subwoofer
https://www.amazon.com/Polk-10-Inch-Powered-Subwoofer-Single/dp/B0002KVQBA/ref=sr_1_2_sspa?s=electronics&ie=UTF8&qid=1548532507&sr=1-2-spons&keywords=polk+subwoofer&psc=1

and have these studio monitors
https://www.amazon.com/PreSonus-High-Definition-Monitor-Unbalanced-Instrument/dp/B07KX6X94W/ref=sr_1_3?s=electronics&ie=UTF8&qid=1548533350&sr=1-3&keywords=presonus+eris+e4.5

I have my record player hooked up to the RCA input of the subwoofer with this adapter connecting the subwoofer speaker level output to the studio monitors' rca input.
https://www.amazon.com/gp/product/B009B8EJYU/ref=ppx_yo_dt_b_asin_title_o04__o00_s00?ie=UTF8&psc=1

The subwoofer is quite loud, but the studio monitors are suddenly very quiet, to the point where to hear them I have to turn the volume all the way up. They are both powered, so I'm not sure why that would be the case. Any advice would be greatly appreciated. All the cables seem to work normally and the studio monitors work fine when used independently.

 

[jsmithepa]

The only thing I can surmise is the attenuating cable is doing too much, but I have no idea what is the standard if any, or whether they may sell a variable type attenuator.