Inspection My new 25-31 PC-Plus arrived in excellent condition, the box looked brand new with no dents, dings, or other signs of UPS tomfoolery. Must be my lucky day! I opened the package to find a subwoofer nicely wrapped in clear plastic with foam inserts surrounding it to shield any blows from the outside world. Upon removing the sub from it's protective surroundings, my first impression was very Keanu-esque...."Whoa". The 25-31 is the smallest in the line of powered cylinders, but the website does not do justice to the sense of mass this thing exudes! It measured a hair under 17 inches in diameter and almost 33 inches high from floor to grill. The unit is VERY solidly built--the cylinder is rock-solid and exhibited no give when given a bear hug as I hauled it down to my basement. I also want to mention that I was fortunate enough to receive a B-stock unit, knocking $50 off the price! Though it was B-stock, I couldn't tell...it still emitted that smell of "ozone" from new electronics and "new car smell" from the automotive grade fabric covering the cylinder. The unit was scratch-free and looked like it came right off the assembly line. If you get a chance to buy a B-stock item...go for it! You will have no regrets. Setup / Calibration I placed the sub in a rear corner of my L-shaped 5800 cu-ft basement, approximately 16 feet from the prime listening spot. I chose this corner as the sub is completely conceiled behind an old recliner. I hooked up my BetterCables 12 meter Silver Serpent RCA cable between the line-level input on the 25-31 and the subwoofer pre-out of my Denon AVR-5800. I switched the cross-over to disable (leaving the cross-over duties to the THX-certified receiver). Phase was set to 0 degrees, Auto-on enabled, volume 1/4 up, subsonic filter at 25 Hz, all ports open. I entered the Denon's setup mode and set the subwoofer channel to -6 dB, (range is -12 to +12), and disabled the peak-limiter. A quick spin with Avia and my Radio-Shack meter set the 25-31 at 88 dB, with my Paradigm Reference Studio 60's, Studio CC, and Studio ADP's all calibrated to 85 dB reference (00 on my receiver). Factor in the Radio-Shack correction factor of roughly 2-3 dB and the sub is running 5-6 dB hot. Hey, I've got a big room here! First Impressions By now, I was really anxious to fire this thing up! Not thinking twice, I threw in Fight Club and went straight to the airplane-collision scene. I set my receiver to -10 (10 below calibrated reference) and queued up the scene.....SLAM!!!! I was shocked by the intensity of this scene...I did a quick glance around the room to make sure it wasn't disintegrating! I grabbed my Radio Shack meter and held it at the prime listening spot and reran the scene. On C-weighting, Fast, I hit 113 dB!! That is possibly 115 dB (with correction factor) at 10 below reference, 16 feet away, in a 5800 cu-ft sonic black hole. Did I mention the volume on the sub was only 1/4 of the way up? This is serious bass. I ran through LOTR:EE....very DEEEEEP. I felt what can only be described as a kick in the butt about a half-second after the ring hits the ground during the opening sequence. Hmm...never felt that before! The resulting Sauron explosion produced a room-rattling experience that I could feel in my chest and in the couch. I must mention that my basement is a concrete slab, covered with carpet and completely finished. I have read numerous threads about losing couch vibrations when placing a sub on concrete, but I experienced no such thing. The 25-31 PC-Plus has the power to rattle my couch, chest, hind-quarters, and walls...no exaggeration. I tried the same scene after re-tuning the sub to 20 Hz by popping in the included port plug and setting the sub-sonic filter to 20 Hz. I can't say that I noticed an appreciable difference. The Sauron explosion was slightly less chest-thumping, but the walls and couch rattled a bit more. I thought I might like that really low stuff, but IMO, the increased rattling of picture frames and other unknowns detracted from the sound quality. I retuned back to 25 Hz and regained the chest-thump, while reducing the rattling slightly. This is all a matter of individual taste, mind you, and it looks like I prefer the higher tune. Conclusion The investment I made into the 25-31 PC-Plus was WELL worth it! I have never owned a dedicated sub before, as my Studio 60's plunged into the mid-30's. This worked fine for an apartment, but now that my wife and I have purchased a house, the added headroom and sheer power of this sub made a huge difference in my home theater. Upon hearing the sub, my wife asked me if the foundation would be able to handle it..."I guess we'll find out", I said.