Cerwin Vega LS-15, troubleshooting help?

[Half Pint]

Hey guys, new here, trying to build a nice 2 channel system, just got a set of Cerwin Vega LS-15's for free, popped a new fuse in each and they sound like new. Here's the issue..

They sound great, even with a crappy RCA 300watt 5.1 from the late 90's, all 3 channels scream, bass is excellent, those cones really move!

I then hooked them up to my NAD 3080 (circa 1977) and there is no bass whatsoever, woofers don't move. Yet the NAD powers my other 2 pairs of 3-way floor speakers very well.

Any ideas why these speakers are not working the same with my NAD as they do with the RCA?

 

[LAB3]

What are the other speakers power specs?? The NAD is 90 WPC @8 Ohm........... my old Cerwin Vega AT-15 needed a 150 WPC amp to really push the woofer hard, and they worked better with my old Yamaha 200WPC amp.. What Ohm is the LS-15 as I have not kept up with CV after Pop gave me his Cornwalls... my son still has my AT-15 and they still sound great. Look at the WPC and the Ohmn for each amp and the same specs for both pairs of speakers. I bet the 400 watt LS-15 just need more WPC and maybe the NAD is not up to spec anymore. Just a good guess...

 

[STRONGBADF1]

Simple things first...

Make sure when you swapped the wires that you didn't mess up the polarity. Double check to see if the negative goes to negative and the positive goes to positive. Also make sure that all the setting are set flat on both receivers.