I've listened to these three amps and think very highly of them all.
The high power amp that impresses me most isn't on your list. It's the big GamuT stereo amplifier, called the S300. This is a 300-watt amp that weighs 400 pounds(!), so the power supply is humongous. And, the amp only uses a single output device per channel, whereas (to the best of my knowledge) all other high-power amplifiers use multiple output devices. So instead of having a chorus of closely-matched voices, you have a single voice. The coherence is extremely engaging - reminsicent of a single-ended triode amp. And the dynamics are absotlutely unmatched in my experience - at Ole Christensen's demo (using Wisdom Audio speakers) the sound was incredibly lifelike, whereas before I had been very un-impressed with the Wisdoms (driven by Edge amps, the Wisdoms sounded lifeless to me). The volume in the GamuT room was so high I had to shout to the person next to me, but the music didn't hurt our ears! I have never encountered that phenomenon before except with live music.
Needless to say, the big stereo GamuT (or the 600 watt monoblocks build on the same chassis) would be my first choice in a superamp. I don't have a pair yet, but one of these days...
Getting back to your original question, I'm not sure which amp I'd choose between the Edge, Halcro and Boulder. I agree with Mike Lavigne that there was a wonderful synergy in the Edge/LumenWhite room, and if Mike is putting the Edge amps in the same league as his Tenors then that is very, very high praise indeed.
The high power amp that impresses me most isn't on your list. It's the big GamuT stereo amplifier, called the S300. This is a 300-watt amp that weighs 400 pounds(!), so the power supply is humongous. And, the amp only uses a single output device per channel, whereas (to the best of my knowledge) all other high-power amplifiers use multiple output devices. So instead of having a chorus of closely-matched voices, you have a single voice. The coherence is extremely engaging - reminsicent of a single-ended triode amp. And the dynamics are absotlutely unmatched in my experience - at Ole Christensen's demo (using Wisdom Audio speakers) the sound was incredibly lifelike, whereas before I had been very un-impressed with the Wisdoms (driven by Edge amps, the Wisdoms sounded lifeless to me). The volume in the GamuT room was so high I had to shout to the person next to me, but the music didn't hurt our ears! I have never encountered that phenomenon before except with live music.
Needless to say, the big stereo GamuT (or the 600 watt monoblocks build on the same chassis) would be my first choice in a superamp. I don't have a pair yet, but one of these days...
Getting back to your original question, I'm not sure which amp I'd choose between the Edge, Halcro and Boulder. I agree with Mike Lavigne that there was a wonderful synergy in the Edge/LumenWhite room, and if Mike is putting the Edge amps in the same league as his Tenors then that is very, very high praise indeed.