It is good to remember that there are other setting that affect how crossover setting work and that it also varies a bit by manufacturer. Another thing is that at least better AVRs allow you to set different settings for multichannel and stereo. Thirdly, you should keep in mind that there are multiple crossover settings, one/many for speaker channels, one for LFE.
For example, with Denon 3808 and movies (DD/DTS) I have all sepakers (5.1) set to small, cross over at 60hz for front and surround (40 for the center) and LFE crossover 120Hz. This way I utilise the speakers relatively good sound quality (MA RS AV set) while getting the full punch of the subwoofer for special effects.
In other words I dont want my subwoofer to get too much involved on medium bass range while subwoofer should take care of the LFE range fully. I also use audyssey for multichannel in order to optimise multichannel sound for the speaker distance variations and multiple listening positions.
For music (stereo) everything is very different. Firstly, I want to use direct mode so no audyssey or any other sound processing will occur. If you have good enough speakers and good source, I think this is the best way to go. While Audyssey can improve the sound in case of poor acoustics, it also colors the sound, usually into something much much worse. If you never listened to music with all audio processing off, please try it out. You migh be amazed.
Secondly, because there often are problems with the room acoustics, you really need to find a proper combination of crossover settings and best possible locations for speakers.
I have had big problems with thumping and exaggerated bass. Depending on the music, sometimes bass is ok, sometimes purely annoyingly "thumpy", sometimes boomy, sometimes as if the bass track had been separately mixed in by someone without proper skills (which can, of course, be the case sometimes
).
Besides improving the positioning of speakers (actually moved them 10cm away from the listening position, which is more than 3m) I finally figured out a good combination for Denon 2 ch direct/stereo settings, for my room.
According to instructions and advises, from various forums, I had originally tried to run the speakers as small and subwoofer as LFE+main, with crossover at 40-80Hz. Might be that this could work with a better subwoofer (than MA rsw12), but in my case this results in a very boomy, unnatural bass. If I play music without subwoofer the sound quality is better, but the boominess is still there.
The best combination was to set front speakers (RS6) to large and subwoofer to LFE+main with crossover of 100Hz. This way I get the better sound quality from front speakers in lower frequencies plus the subwoofer actually lessens the thumpiness (is that a word) and boominess (or that
), creating a much tighter and controlled bass.
It can take a lot of time and effort to find out the right sound settings and position for your speakers, but its definitely worth it specially if you listen to high quality music a lot