This is for newer folks here, like me. All you more experienced sub guys and gals probably already knew it, so all of you can laugh out loud here. (Sub-guy? Does that make you less of a man?)
I'm a sound hobbyist, most doing DJ/PA work for fun, family, and friends... picnics, parties, receptions, etc. as an escape from my day job. I got a little tired of it and sold all my equipment a couple of years ago, but then started missing it and recently began putting together a sound system again.
My equipment is mostly pre-owned and generally "better", if you use the "good", "better", "best" way of classifying it. I'm not a brand-snob, and generally buy what I can afford when I find it at a good price, as long as it's quality equipment and fits the rest of my system. In my previous system I used EV T252+ cabinets with a pair of Mackie 1400i amps. These cabs seemed to have plenty of bass for what I was doing then, and although I used a pair of Peavey dual-18" subs with them for a short time (with another pair of Mackies), that was too much, and I didn't keep the Peavey subs. OK, this is the point where you can all start to argue whether my above-mentioned equipment choices are "quality" or not.
This time around I came across a pair of EV SH-1502ERs and that's where I started building the new system. (See my post from a couple of months ago, "best sub for EV SH-1502ER?".
Anyway, enough background... on the recommendation of several folks here, I bought one Yorkville LS608 sub and have played with it last weekend and some this weekend... still in the "getting-to-know-you" phase.
Here's the frustrating part that you can all laugh at and the newer folks can learn from: Everything worked fine when I was plugged into the 1/4" jack on the back of the sub. When I tried out the Neutrik connection on the back of the sub, NOTHING. Long story short, I tried every possible combination of jacks and cables between the back of the amp and the back of the sub. Every time I used the Neutrik connection on the sub, I got nothing, every time I used the 1/4" connection it was fine. I couldn't for the life of me figure out what was wrong. I questioned and cussed that sub, Yorkville, the place where I bought it, myself, the garage lighting, and a host of other things.
Yorkville's website mentioned the Neutrik configuration switch on the sub's connector panel, but didn't really say much more about it. Newbie that I am, I ASSUMED THAT THE SWITCH WAS IN THE CORRECT POSITION as it came to me from the factory. IT WASN'T!!! Figuring that out took an hour of frustration, doubting my own sanity, and even getting ticked off at this website because I couldn't login! I got into some sort of endless loop where I was told my password was no good and I had to reset it. Every time I reset it and tried to log in, I got the same message that the new password was no good and needed to be reset. I finally gave up on that. This was well after work on a Friday night, and I didn't even try contacting Yorkville.
Bottom line, check that little switch. If you get no sound out of the Neutrik connectors, that could be it.