Last night, while moving my sub around the room to find the best sounding bass, I tried something for the first time and I am confused as to the meaning of the result. A while back I plotted my bass response curve using only the sub (had to disconnect the front mains) but I used a series of test tones and it sounded like what I expected. Last night, however, I disconnected the mains and ran music through the sub only. I did this in two ways. My main CD player is my Cambridge Audio 540D DVD player. It allows me to set the mains to small, sub on and applies the crossover/bass management to two channel regular CDs. The manual (which is pitifully thin on info--my biggest complaint about Cambridge (Arcam is also thin on info in their manuals--must be a Brit thing) doesn't state the crossover frequency but after some exhaustive research I've learned that it is supposed to be at 80hz. I have no idea what the slope is. In my receiver, I can set it anywhere from 40, 60, 80, 100, 120, 150 (globally for all speakers) and the slope is said to be 12dB high/ 24dB low pass. My player is connected via analogue cables to the multichannel input of the receiver, where I engage "Pure Audio", which completely avoids DSP and lets the player's signal through. The player is also connected via toslink to the receiver so when I select the CD input on the receiver, I can use any DSP setting I want, should I wish to (sometimes I use Pro Logic II music mode for some of my two channel CDs). By switching from the M/C input to the CD input on the receiver (each input remains in the last setting used, so M/C was in Pure Audio and CD was in Stereo (which uses the receiver's crossover and activates the sub), the difference in sound from the sub with no mains was both startling and not at all subtle. In each case the xover is supposed to be at 80 hz. With the player doing the xover, the sound was articulate, one could clearly identify the bass guitar and the kick drum as separate instruments and there was more information coming from the higher frequencies (I don't have the instrumentation nor the knowledge to measure actual vs stated crossover frequencies and slopes so I'm going with the settings as stated). With the receiver doing the xover, a lot less higher frequency info was heard clearly, and the lower frequency info was muffled, inarticulate and boomy. The sub was in the identical spot throughout (all I did was toggle back and forth on the remote). My friend and I preferred the player's xover management for music, by a long shot, both with the sub alone and later with the mains engaged as well. We were trying to figure out which unit had the steeper (or shallower, I suppose it depends on your point of view) slope. Neither one of us is an engineer or physicist and we reasoned that the player's slope was steeper because the area under the curve was larger and thus contained more information than a shallower slope. I'm curious if we are correct (it's a fifty-fifty chance, the way I see it). Regardless of steeper or shallower, I know that I prefer the player's management. I'd like to know if the player has the steeper or shallower slope, though, as in the future, I would likely prefer a replacement machine (should the need arise) that gives me the more articulate, cleaner sound. Of course, another possibility is the player's xover is not 80 hz, but something else entirely, but I have no way of checking that myself. I compared the player to the receiver set at 100 hz, to kind of explore this hypothesis, but found the player's sound preferable and more articulate. I'd love any thoughts or explanations on the subject. Thanks.