[dyohn]

I do not like the Behringer amps, but they work well for many people. Try contacting Bob at CSS. He carries several subwoofer plate amps, and his drivers are top-notch as you already know if you're using an SDX15. Perhaps you simply need to use a larger amp, or build a new enclosure for your existing driver?

 

[dyohn]

I owned a Behringer EP1500 and an A500. Both were exceptionally noisy (both signal noise in the audio spectrum and because of fan noise) and neither was anywhere near as powerful as advertised. But like I said, many people really like them because they do offer a lot of output for the price, and there are mods available to quiet down the jet engine fans.

 

[dyohn]

I measured the amps outputs using an o-scope. The A500 produced nearly 25% THD at rated output into a resistive load, and yes it did sound terribly noisy running full range. The EP1500 was not quite as bad and since it was powering a subwoofer high distortion like that is far less noticeable, but the fans were unacceptably loud to me. Use the 4000 and if it suits your requirements then that's all that matters, eh?

 

[dyohn]

Yes, the fan noise problem was with the Ep1500. Perhaps my A500 was defective, but not only was the THD unacceptably high the S/N was very low and there was plenty of audible distortion driving 8-ohm loads. If it was unique to the sample I had then perhaps it speaks more about their quality consistency than to their design.