I've had a few Morrow cables in my rig for a few years and I purchased (using their deal of the day) a new PH5 phono cable arriving today to serve a new turntable. I like these cables for phono and interconnect usage especially in my rack where flexibility helps. I use more massive power and speaker cables from another company downstream to my amp and speakers where they lay on the floor. Using Morrow's omnipresent sale offers I think you get a pretty good cable at value pricing. I don't go beyond their level 5 however as other brands start to beat them at similar or lower pricing. Just my opinion there.
The break in process is not that big of a deal IMO. I let them run their course as I enjoy my music. After awhile I notice the sound isn't changing any more. My cables from the "other" company as well as some phono cartridges have the same lengthy break in requirement so I don't sweat it.
I am able to hear the basic characteristics right out of the box. The sound doesn't really change as much as it clears up and becomes more transparent, which allows the frequency extremes to be more noticeable. An upgrade should sound like one immediately only to get more refined as it breaks in. If is doesn't beat your existing cable out of the box you didn't aim high enough IMO, or you already have cables that you like.