Me and a couple of buddies went to tonemerchants.com... we took our guitars (all Ibanez's - 1 AX, 1 S2020X, and 1 JEM777VBK) and took a drive to OC a few weeks ago to test the only "demo" model on the floor and it was plugged to a Mills 4x12 cabinet... my buddy was so impressed with the head he placed a deposit for 2 of 'em (for him and my other buddy)... hopefully they pick it up this weekend cause I wanna hear what that head sounds like through my Mesa 4x12

and I must say it's one of those amps that will make you go "wow... is that what i've been missing out?!" after striking that first chord. Of course, any guitar plugged to a VHT amp will react and sound different but between the 3 guitars we plugged into, the only consistent thing was *THAT* VHT voicing.
Each of the 3 channels can be configured for "low" or "high" power (40w or 100w). Notes are very articulate and clear, both in clean and dirty channels. Best part I dig about the Sig:X is the way the amp's foot control "remembers" your last preset... like for example, channel 2 (yellow) is your "marshall" tone with the FX loop and Boost on while your channel 3 (red) is your "balls-to-the-wall" grind with those two switches off. It'll remember those "settings" when you change from channel 2 to 3 and back to channel 2. I'm even surprised that the amp isn't MIDI-capable (though I'd think it'd be overkill for a $2k head).
I also dig their "Dynamic Sensing" technology... I can't quite explain the technicality on how it works but it's kinda like a "sustainer" built-in to the amp... it senses when a note is sustaining and it sustains the hell out of it...
My only other experience with a VHT is with a Deliverance 60W 2x12... and I must say the Sig:X is like 3 Deliverance's in a single head... it's that versatile.
Reg