Short list of musical subwoofers

Describing a sub as "musical" is odd. Turn everything else off except the subwoofer and play a record. Does that sound musical? Aside from the sub moaning and thudding away you will also get to hear the rest of your environment buzz and rattle. The music masks it. Subs add visceral impact to the music and when used correctly unload the bass from the main speaker increasing headroom and lowering distortion. I suppose you could say they make the main speakers more musical. None of the subs mentioned incorporate a high pass filter for the main speakers so one might assume that none of them are musical.

If you are at all handy look at the subwoofer kits Parts Express sells. They are a bargain. Two of them with a two way crossover would be substantially more musical than anything above.

@tomic601 , For me there is only accurate and not accurate.

Subs come along with a lot of baggage. It is very difficult to keep enclosures from resonating and at the long wavelengths you have at the crossover point phasing and time are critical. All this results in distortion which tends to lessen the impact a sub should have. Digital bass management is extremely helpful bordering on absolutely essential.  There is no commercial subwoofer enclosure that I like short of the Magico Q subs and they are too large for my circumstances. It is better to use multiple smaller subs than one or two very large ones. By smaller I mean 12" drivers vs 15 or 18" ones.  

@lanx0003 , That is a great first step. Good for SVS.  I disagree about high level connections. The best way to integrate subwoofers is to use digital bass management which is a combination of "room control", crossover selection and Time/phase correction. If done at 192/24 with a 64 bit processor the corrections and crossover are invisible and the improvement in the system's overall performance is something I wish everyone could hear. All this could be done in the context of an active subwoofer but it doesn't seem the industry thinks consumers will pay for it. Personally I do not like active subwoofers. Passive subs allow much more flexibility and if you build the subs yourself from kits or your own design the savings can be huge. There are many excellent subwoofer drivers available. There is absolutely nothing special about any of the commercial subs. The key to low distortion is large and multiple drivers keeping excursion distances down. 

@tomic601, there is not just one best but several best solutions depending on the room and main speaker type. No system is perfect including mine but perfect is a good target to shoot for. Commercial subs are a matter of what colorations you can tolerate most. There is no such thing as a "musical sub."  You can use subs to make a system more musical. The trick is in doing as little damage as possible. Many people refuse to use subs because the applications they have heard do more damage then good or perhaps they had a bad experience. This is more common than not.  There are contradictions in use that have to be balanced. A good example is the crossover point and slope. The higher the crossover the more you clean up the main speakers but subwoofer drivers produce very colored midrange and you have to keep them low enough to avoid hearing them in the midrange. You can use steeper slopes but doing so can make the sub more noticeable as the transition becomes sharper. Digital bass management allows you to experiment with crossovers to find the right solution for your system. I can change crossover points and slopes on the fly from the listening position and AB solutions. 

If anyone thinks a subwoofer is musical, turn the other speakers off and have a listen. If that is musical perhaps you are smoking too much weed?

@lanx0003 , phusis hit the nail on the head. The benefit of using a two way crossover increases the wider the frequency response of the main speaker's woofer. Speakers with a large woofer that only covers the bottom 250 Hz are not going to benefit as much as speakers with smaller woofers that cover the bottom 1000 Hz. This includes a big chunk of the midrange where the decrease in distortion is very noticeable. With full range loudspeakers like my Sound Labs IMHO it is mandatory. You turn a polite speaker into a disco rocker. There are other advantages. If you are using digital bass management which includes the crossover you can place the subwoofers where they work best and are most efficient (in corners and against a wall) and correct them so they match the mains speakers in time and phase. If you like to feel the kick of a bass drum you can consider this mandatory. If you have a low power main amplifier like a SET this is also mandatory IMHO. You will increase your headroom and keep the SET away from clipping. 

The manufacturers know that most people are cost and complexity sensitive. Using just a low pass filter and pulling the sub in under the main speakers is an inexpensive, easy way of running a sub. If you have to start out this way as a temporary measure to get yourself into the game, go for it. Down the line get a preamp with bass management or a crossover like the MiniDSP and you are really in business. There is a tendency to dis digital equipment but IMHO the benefits far outweigh the disadvantages. There is so much you can do in the digital world that is impossible in the analog world. My days of being a purist are long over and I never plan to look back. Being able to tune your system exactly the way you want it is a huge advantage. The trick is to keep everything digital until the DACs before the amplifiers. This means you have to digitize your phono stage but if you do it in 24/192 the conversion is invisible.