Excellent Tube DAC/Amp
A great choice for anyone who wants tube sound and power on the go. Clean and simple to use interface on the LED screen allows you to manage every aspect of this seemlessly without needing to go into an app. Transition between tube and AB mode is seamless, and the filters do noticeably affect the sound. Build quality is solid, I'm very fond of the mustard case, and everything is quite compact, albeit larger than a more typical dongle.
Overall, wide soundstage and excellent resolution. The treble is slightly rolled off in tube mode, but not so much that you completely lose detail--it just softens the high end a smidge. Bass reproduction is strong and the mids are wonderfully smooth. Tube mode adds exactly the coloration you're expecting from a tube amp, making the overall signature soft and warm and dreamy. I run it on the NOS filter, but the fast filter brings back a touch of detail when in tube mode, if that's a concern.
I gave it four stars, despite incorporating it into my daily portable kit, for two reasons. One, while it produces plenty of power on paper, I listen somewhat loud and frankly find that the 3.5mm unbalanced output leaves me cranking it to the upper end of the volume range, even on high gain, so I always use a 4.4mm balanced termination. Second, it is fairly warmly colored in tube mode, and smoothed across the frequency range, which can affect macrodynamics. While that's presumably something you're looking for, I also found that the added low-end harmonics didn't mesh well with an all BA IEM (CFA Andromeda Emerald Sea) and that my set with a dynamic driver handling the low end (CFA Dark Star) fares much better. That may not always be the case, but it was marked enough between these two sets that it seemed worth mentioning.
Overall, I love this little device and, as said, now take it with me everywhere to power my Dark Stars. YMMV, etc etc
