Thanks guys for all the input, much appreciated
I've been listening to some music, moved a sub here and there as far as my short cables allowed, done some rough measurements. I think I'm ready to share some impressions, doubts and observations.
The good.
Initial setup was really easy with my LSR305 monitors. Throw it under a desk - check. Set 80 Hz crossover - check. Set same volume as monitors - check. Confirm volume match with REW - check. Done. Basically plug and play.
And it immediately made all the music 90% more awesome. Didn't change it, didn't reveal anything new, I could hear all the notes before, but it just gave them proper gravity back. I played a bit of bass guitar long time ago and I must say this is much more like it. Now I feel my ears being squeezed in like I remember.
But what stunned me the most was how good it works in low volume near field. It's immaculate. I can feel every beat through my desk and mouse and it's perfectly linear with the volume slider. Even at night, when kids and wife are asleep - I can throw in some crazy dub track and get enveloped in whisper-quiet yet properly fat and smooth bass that somehow doesn't leave the room and doesn't bother anyone up.
As it works as a new footrest now, feels very sturdy and nicely baffled. The whole box barely vibrates even at high volumes. It can move impressive amount of air - I can immediately feel the wind from a meter away and yet it's completely silent. Just like with my wife.
The club setting (XLF) is absolutely ridiculous. Completely useless, stupid amounts of loud booms, probably designed for simpletons at drunken frat parties. Love it. It will certainly impress some of my friends.
The bad.
Although sounding generally right, there is one crucial thing missing. Those lost 10% of awesomeness. The chest kick. Anyone who had the pleasure of standing next to a drum set should know what I'm talking about. Properly rocked kick just rips the breath out of you and shakes the blood in aortas. And it's just not there. I expected a bit more from such a big and heavy package. I came to a realization that my music collection includes things like soundtracks and with those the sub slightly under delivers too. I went through usual Zimmers and Daft Punks. Pumped the sub volume up. Engaged warp 11 and put the frat boy XLF on. I could see the desperate draft from the port moving the drapes, but couldn't feel the drama. That's where the buyer's remorse kicked in - maybe the SVS SB-1000 was a better choice? I whipped the mic out and started investigating...
The ugly.
See my measurement at the desk. Bass basically ends and leaves home at 38 Hz. My monitors on their own don't measure much higher. WTF? And this is a studio sub? Where is my extension to 27 Hz??? I mean, I got it for cheap, but not this cheap.
Reversing polarity didn't change much:
Feels like I'm being robbed of those precious 10 Hz below 40. Maybe there's my chest kick hiding, or at least big part of it? I've started going around a room with the mic. Here are the measurements:
On the couch:
And measurement from the opposite corner of the room:
All of those were taken with the 80 Hz crossover. Rough, single measurements from hand, so don't look much into higher frequencies. Smoothing 1/24.
I can't really work from the opposite corner of the room, so I started wondering if moving stuff around would help. The issue is that I'm limited to PEQ, so no phase trickery for me. Also, can't really test with different positioning much for now - need to order longer cords.
For reference - this is my current arrangement. I've tested the sub under the desk from left to right and so far this is the best position:
It is not very optimal for a lots of reasons, I was thinking about the general remodeling for years and now it's good time.
There is a slanted ceiling situation going on and I haven't found definitive info on optimal speaker placement in such conditions. My measurements give me slight hope - maybe moving everything to the other side could be beneficial? Something like this:
