My brief, short, simple impressions after spending a couple weeks with the X-Sabre:
Sonically:
I find the X-Sabre polite and tame. I believe it presents the music as is without adding or subtracting anything. Nothing seems odd. Certainly isn't shouty or fatiguing. I can't really comment on the characteristics of the DAC in terms of FR and details such as resolution, imaging, etc. because I really have no reference point, nor do I have another DAC beside it to compare at this time.
vs. W4S DAC2
At first listen, the W4S sounded more appealing with the HD800 and Stratus. Vocals were more forward, and the overall sound was engaging. Then the fatigue kicked in, and the fact that the DAC2 is a bit top tilted didn't help either. Voices were shouty. Oh God Norah Jones was stabbing my ears.
The X-Sabre in comparison was more laid back, and a bit less engaging. However, I think it'd be safe to say the X-Sabre is more neutral than the DAC2. Vocals weren't as prominent as the DAC2 was but I'd take more laid back than fatigue.
vs. Gungnir
The entire reason why I sold the Gungnir was because it sounded shouty and hurt my ears alot. Norah Jones would destroy my soul every time I'd listen to her...
X-Sabre? Absolutely no fatigue due to vocals. None. Nada. Don't Know Why sounds so sweet and lush, there's no excess grain and it sounds balanced overall. I am using the Mjolnir and LCD3, just like I did with the Gungnir.
Switching to the HD800, still no shoutiness, no fatigue, no ear bleeding. I'm loving this.
I think the FR signature of the two DACs are quite similar: not bright, nor dark. HD800 sibilance quantity seems to be the same with the Gungnir and X-Sabre.
Piano sounds normal on HD800 but sounds a little bit slow with the LCD3, though the effortlessness and openness is great vs. the Gungnir. Someone somewhere said the Gungnir sounded tense. I 100% concur with this description, and the X-Sabre offers a relief of tension.
w/ Mjo:
LCD3 sounds incredible, maybe a teenie bit slower than HD800 which wasn't a trait in the other DACs (maybe due to less shout?), but sounds sweet and balanced, nothing added, nothing subtracted. If I didn't sell my Mjolnir, and if I didn't buy the HD800, I'd end game here, no joke.
w/ DNA Stratus:
LCD3 sounds terrific, but the bottom end is a bit bloated thanks to the tubey goodness, and a tad slow. I think this is because the X-Sabre is more neutral with no added treble and more laid-back, causing the natural characteristic of the Stratus and its tubes to be betrayed. Vocals are oh so sweet, and the dynamics and imaging is wonderful, although I keep thinking the soundstage sounds like a V where there would be missing space at the widest points but deeper into the sound. However, it's not as bad as it reads; it just gives me a "feeling" but it's not cut in stone. I think a lot of it is because of the recording quality. I just wanted to put it out there.
Lots of sub bass. HD800 was almost as sweet, lush, and thick as the LCD3 without as much sub bass, but had better impact. Again, no vocal fatigue thanks to the X-Sabre.
I think the Stratus would benefit more with a more forward and top tilted DAC like the W4S. I don't want to extrapolate and hastily generalize tube amps, but at this time I'd like to suggest that the X-Sabre will suit an SS amp or an SS sounding tube amp like the Super7, better than tubey sounding amps like the Stratus and Woo amps in general. Now this is before rolling tubes, so keep that in mind.
Physical qualities:
The X-Sabre is built like a tank. I was just astonished at the build quality. Super hefty and feels solid as a rock. Great and effective feet. Simplistic, humble design, nothing flashy. Nice clean white LEDs and easy to read and interpret labels. Two switches that are obvious to operate; great quality, no looseness. It does attract lots of fingerprints but they're easily wiped off with a cloth.
I just wish it had toslink optical input!
Please take my impressions with a bag of salt, I'm not nearly as experienced enough to write like six moons, nor do I have golden ears. I'm just your average Head-fier with a sense of reality and an open mind, who likes to listen to all genres but death metal and heavy rap.
