Apologies for not writing the review of the Lab12 Ref' that I promised. TBH I couldn't find the motivation. It was 'ok'; perhaps a little more than ok bearing in mind its pricepoint. But, in my set-up and room the music didn't move me. Transients were slow, detail didn't impress and I experienced a higher frequency range troubled by metallic leading edges - digititus, if you will. I detected none of the attributes one might associate with tubes in the traditional sense i.e. presentation with a whiff of warmth etc.
It's funny you should be considering Le Dac 2 - because that is where I spent my money in the end. It's just in an entirely different league - as it should be given the cost difference. The attributes you describe as wanting in a DAC are precisely what the Metronome is all about. It's presentation is not as forward as some - a T+A 200 I had on direct comparison was very strong in this area - but musicians are certainly present enough and, unlike a very forward presentation, I can listen, happily, for hours. But that's not to say it's laid back to the point of 'sleepy'. It tends toward a slightly 'romantic' presentation. Absent are hard edges, and the kind of short, fast decays associated with the in-your-face, relentlessness which initially sounds amazing but soon wears thin. It's wonderful with, particularly, solo vocals and classical, but it rocks and clubs, too. Piano is a great test of any dac/system - Le Dac 2 does it true and authentic. Ultimately, it revealed a deep level of emotion in the music to which it connected me - and you can't ask for more than that.
What's become a big deal is the Metronome's i2s input. I've always struggled with USB's frequently negative impact on smoothness. I bought a used Marix S/pdif, powered by S Booster (goes between Melco server and Le Dac) so I could test the i2s input and it's unquestionably another step up. The USB input on the Le Dac is by no means deficient, but I did find sound to relax and smoothen further via i2s. The Matrix clock/FPGA processing may be playing a part in this, too. Detail seems to rise a little across all frequencies and I can see 'into' the music further. I won't go back to direct USB. Metronome have just launched a streamer and, though I don't need one per se, I will try it in place of the Matrix to see if its i2s output produces a result even better than that of the Matrix.
I absolutely recommend you demo' the Metronome. I reviewed it here:
https://www.whatsbestforum.com/threads/metronome-le-dac-2-review.37030/#post-888412