|But if you have two amps of different designs that sound at least similar, I would still be inclined to buy the better designed amp that runs at thinner (or non-existent) profit margins. That is the very definition of value for money.
Having heard both the M^3 and the HP100, to be honest, I personally didn't find them to sound similar
To be more specific, the soundstage on the HP100 had a more 'holographic/3d' quality that the M^3 couldn't provide. In terms of the lower end, the HP100 went just as deep, but was tighter and cleaner. Mids were also thicker and the highs were crisp and clean without any harshness.
Now that I use the HP100 with a Pico for the DAC and the Audio Technica ATH-AD2000 as my primary cans, it feels that the Pico is the limiting factor in my rig, while before, the M^3 would be on par with the Pico. My next purchase (hopefully) is an MHDT Havana DAC
I think a lot of the issue is that the HP100 is not as popular as the M^3, so aside from Head-fi meets, there are quite a few people who haven't had the chance to hear it and make a comparison based upon the sound rather than design.
In all fairness, the M^3 was an incredible value for the money at the $300 to $400 range, no doubt about it, hands down, and I by no means would ever knock it. But when you throw in the S11 PSU, it could jump to ~$550 ($370 for the M^3 + $180 for the S11)
The HP100 now goes for over a grand ($995 + $85 shipping), but at the previous price of $680 ($595 + $85 shipping), it was easily just as good of a value as the M^3. And having heard both, if I could go back, I would have spent the extra $100 for the HP100 ( assuming the old price of the HP100 and the higher price of the M^3
But of course without trying the equipment out, there would have been no way to know with any certainty
And as mentioned before "You have to hear it yourself and decide whether it's good or not."