I listened to the D6's extensively and compared them to several others... Hertz, Infinity, Boston, Focal, and a few others... the D6s had lifeless vocals, lacked detail, and had poor highs. Honestly the worst of the bunch. The only thing they excelled in was midbass, but the Focals and Hertz easily matched them there and beat them in everything else.
The HEX series were better but not enough to justify the extra cost.