So far, this is hands down the best solid state amplifier I've ever listened to. Maybe it's psychoacoustics, but I've never heard the Stealth sound so good on an amplifier (other than the Nautilus). However, I know for a fact I'm not the only one who has said this about the HM1. From what I can tell, Class A + Servo mode is the way to go for both the Stealth and D8KP LE. Class A is more forward to my ears, but Servo mode has an almost tube-like quality to it in terms of laying back a bit and opening the sound up.
The EQ knobs do a great job of subtly fine-tuning the sound without going overkill. For the Stealth, I like maxing out the bass EQ and set the treble to +1. For the D8KP LE, I keep bass maxed out, but I reduce the treble to -1 because on some tracks I find it a little sibilant.
As
@GoldenOne mentioned in his review and earlier in this thread, the soundstage knob at +1 is the perfect setting for the majority of songs. It really creates a grand sense of space with the music. You really feel enveloped by the sound. Even with closed backs, putting the soundstage knob at +1 gives them an almost open-back quality in terms of expansiveness. At +2, I feel it's too much and makes things sound a bit strange.
The HM1 alone really brings out the best of any headphone you throw at it, which is an impressive achievement. However, when combined with a tube amp, it brings the listening experience to a whole new level. The great part about the HM1 is that the EQ and stereo width effects carry through the line outs. By setting the soundstage knob to +1 and then bringing that sound over to the tube amp, it just absolutely blew me away. The tubes add that extra bit of naturalness and airiness that makes you feel you're really there in the studio with the artists. It is INSANE how well this amp pairs with a good tube amp, especially with the EQ and width effects.
To be honest, I secretly hoped that the HM1 was so good, that perhaps I wouldn't need a tube amp. However, the combination of the two leads to such an addictive sound, that quite frankly, I don't think I can give that up.
For those still waiting for the next batch, it's worth the wait.
So far, it sounds absolutely amazing with the DCA Stealth and I haven't even played with the bass, treble and stereo width settings yet. I think I'm leaning a bit towards Class A + Servo mode, but it's hard to decide between the two modes. I guess it depends on the song. Looking forward to trying the D8000 Pro LE with it as well. Once I get a good feel for the sound, I'll then use it as a pre-amp into the Nautilus and see how that changes up the sound.
