Interesting - not 25800 kHz AM or 25900 kHz AM? Sounds like a pirate. The lower part of 26 MHz and the upper part of 25 MHz
25.610 MHz - 26.505 MHz (roughly) is used for all sorts of two-way comms systems, land mobile (taxis, etc.) 5 kHz steps, AM/FM, plus SSB freebanders, marine users and yes the 11 meter broadcast band. Plus 25.87 MHz to 26.47 MHz is used for STL and IFB purposes, but that's not what you were hearing based on the 25.915 MHz AM frequency. 25.910 MHz FM had a nearly steady broadcast link audio on it during the last sunspot cycle peak (along with 25.950 MHz FM and 25.990 MHz FM), but that's gone now (at least on a regular basis).