Yeah, the CAST connection, versus XLR, increased resolution but kept the same "musical" qualities. In some ways, the sound with ACSS had more ease to it making it more musical in a free flowing sense.
With the HE-6's, I would say that the Master 8 is definitely warmer than my DIY First Watt F3, which in turn is a bit more transparent but has piercing highs that left me quickly fatigued. I found the Master 8 to add more body to the highs compared to the F3 for a smoother and less fatiguing presentation. Both amps though have trouble taming sibilance on vocals, and vocals have a energetic quality that sound artificial/synthesized. The sibilance is less pronounced at lower volumes, but sometime I like listening loud.
After having had the privilege of hearing musicman59's TOTL Threshold amp system, I know the HE-6's are capable of lifelike and non-sibilant vocals while maintaining all its other wonderful qualities but IME the HE'6's are PITA to setup properly. I would have given up on them already if I hadn't heard them what they're capable of.
Edited by BoyNamedSue - 12/2/12 at 4:30pm