I see people rate these at five stars and I'm baffled (no pun intended) as to why. The bass section is hopeless, seriously lacking weight and definition, rendering them very poor when used as stand alone left and right speakers. This surprised me because Def Tech quote a surprisingly low 35hz roll off, so I expected more of the Mythos 4. Out of interest I decided to measure the -6db point. It checked out at 55hz so is the 35hz quoted a typo? I suspect it is, due to it's internal volume.
In the blurb Def Tech tell one to set the crossover to 80hz when using them in a 2.1 / 5.1 system, making the mythos 4 pointless. Why not just use another pair of Gems? They will go down to 80hz easily.
Now I don't like writing a bad review but if you are considering the Mythos 4 as your main speakers in a stereo system, then seriously look elsewhere, especially given the price. But even if you are considering them to use as the main L and R in a 2.1 / 5.1 system, the bass section will be rendered redundant due to the 80hz crossover to the sub. So what is the point of the Mythos 4?
So what is the mid-range and treble like. Well sadly not good. The sound has a strange harsh and hollow quality that makes them sound cheap. At this price point there is some serious competition from the likes of B&W, ELAC, KEF and Polk Audio to name but a few. After listening to the mythos 4's for a while I switched to an ageing pair of B&W DM303's (an old favourite of mine) they were reasonably priced and do everything surprisingly well. They blew the Mythos 4's out of the window.
Now, I like Def Tech usually, but I only have experience of their subs so I will be listening to other speakers in their range with interest.

Who are these people at Definitive and what have they done with my sound system? These speakers are the driving force to my Definitive surround sound system, and they bring out so much detail it's shocking. I've finally stopped asking questions and just enjoy them. They don't go real low so you'll need a nice sub which I have, so just know that. Besides that little issue I am very pleased with these speakers. If you like laser like detail, you will love these speakers. Top notch company too, made in the USA.