With EPOS speakers, you will benefit from the Creek/EPOS/Music Hall family synergy. One of the most musical sounding set-ups that I have ever heard was a Creek 5000 series amp with EPOS M15 floorstanders and a Music Hall MMF CD25 cd player. The M12 are excellent stand mount speakers. The EPOS M12/M15 will do justice to much of the No Depression/roots music that you listen to ... my tastes, as well.
If the M12/M15 are too big for your office, it would make sense to look at the EPOS ESL3 mini speakers. For about the same price though, I would look at the NHT SB2. IMO, I think that the SB2 sound a notch better than the ESL3 and are less fussy about placement, given their sealed box design. I have actually owned both the ESL3 and SB2 and the SB2 sounded richer and more detailed with my set-up (Marantz 2240 vintage receiver and Music Hall CD 25 cd player).