Amplifier Output 520 watts rms into 4°

High Cut Filter 40 Hz - 160 Hz adjustable, with an LFE bypass position, and 12 to 36 dB/octave adjustable slope.

12 - 36 dB/octave adjustable slope

Frequency Response 33 Hz - 150 Hz (-3 dB)

So we win and lose some. We get some good and bad news. Either way, testing like this is "very good info to have" in our back pockets. But before we toss this baby out the with the bath water.. read the fine print and manual. There's more under the hood of this AMP andmay be leaping to conclusions on without the manual and specs in hand! This is an interesting case study and little amp.You are correct. This amp has been designed, tuned and operates with the companion sub in a very specific range and load ofA lot of sub makers are DSP programming their amps today to protect the sub and optimize the output. My guess the DSP is programmed to compensate the lower / weaker side of of the SUB unit. So you need to bypass all of that by using the front button to step thru the many modes:andspecifically. I'm thinking that might remove the peaking / compensation but I do not know for sure.The output is rated into 4 ohms. So that'swhere they measured those "520 watts" at some specific.. (my gut says that's what the companion speaker rates to...). (This is why I like to dig into the specs.. YMMV).Here's the link -> https://www.sunfire.com/product/matching-1u-amplifier-hrsiw8-subwoofer-HRSIW8AMP Here's the manual (see the modes and EQ options) -> http://resources.corebrands.com/products/HRSIW8AMP/pdf_HRSIW8AMP_manual.pdf This amp has several modes and I think they need to be defeated to flatten that bump.. but it's never going to get passed the upper range design limit.allows you to choose from five preset EQ settings to suit your listening program:Movie, Music, Dynamic, Impact,LFE/SUB Mode In, the Crossover Slope and Crossover Frequency can be adjusted, and so these menus are available. Inthe Crossover Slope and Crossover Frequency cannot be adjusted, and so these menus are hidden. The crossover adjustment is then left to the Home Theater preamplifier.This AMP is loaded with features too some of us long to see in amps / see the specs: XLR inputs, 12V triggers, DSP processing, Remote controls, ...So some things to think about are should things like this be taken into account when evaluating, testing or measuring? Every AMP we see isin fact theSo everyone is playing with these figures when they can... sadly that's a whole other thread! So if we just consider this AMP is driving a SUB in a limited frequency range does that change your gut reactions? Is is delivering on what the designers intended? I mean it's not a general-purpose 20-20kHz full range amp - never intended to be.So does this make us think a bit differently / out-of-the-box? Hmm.. I am still very disappointed with that claimed power measurement.... who knows maybe its into 2 or 3 ohms - they really don't say which always makes me wonder what details may have omitted. YMMVPeace.