At first I did not care for the initials but it has grown on me especially after I found he reasoning behind it which you can read here in an excerpt from Mariano's blog.
More info from Mariano Conde's site:
On the occasion of the forthcoming CENTENARY of the luthier dynasty to which I belong (1915-2015), I would like with these lines to put on record my role today in maintaining and ensuring the continuity of this celebrated tradition of handcrafted guitar making.
Since 2010, I have continued this tradition in my workshop at 1 Calle Amnistía in Madrid. There you will meet face to face the ONLY TWO LUTHIERS IN THE FAMILY, my son and me (4th and 3rd generations), respectively. There too, accompanying us in the exercise of their craft, are our ONLY collaborators from my former Conde Hermanos workshop in the Calle Felipe V, also in Madrid.
What follows is a description of the particular characteristics of MARIANO CONDE guitars, as well as a NEW INITIATIVE which we have begun to adopt, namely the incorporation of the HALF MOON HEADSTOCK in all our models.
A. – HALF MOON HEADSTOCK. As a homage to the headstock first designed by my father in the 1950s, the flagship emblem of the house ever since then, we have decided to incorporate this headstock in every model of guitar built at our workshop at no. 1 Calle Amnistía. We do this in order to signal the entirely handcrafted nature of all of our guitars and to put an end to the commercial exploitation of this headstock by part of my family through its use in factory-made guitars.
B. – LABELS. – Since establishing my workshop at 1 Calle Amnistía in 2010, I have personally handwritten all my labels on card, together with details of the model, the guitar’s item number and the year of construction.
C.- MC.- The initials MC on the guitar’s soundboard were born of my desire to differentiate myself from other companies selling guitars under the name Conde.