Maverick Audio TubeMagic D2 DAC

Price aside, I'd like to compare this D2 with my current AD-1865 NOS Dac or a friends Metrum Octave Dac.

Would be very interested in a comparison between D2 and Metrum Octave Dac.

Both, the D1 and D1+, use an electrolytic cap with a film bypass for the left and right channels. I swapped the electrolytic's for Nichicon Muse @ 10uf. The film bypass caps were replaced with VCap CuTF .22uf although the original film caps were rated for 1.8uf but measured 1.5uf. The new caps cleared up tonality, tremendously enhanced focus, and widened the sound stage; however, there was a loss of depth with the new caps.
The D2 uses two 2.2uf Wima's as output caps with, possibly, smaller Wima's in series after the larger caps. Squeeze a pair of Jupiter VT stacked caps in there to open the stage and give the music natural timbre.

D1/D1+ tube trials:

GE JAN 5670W: This tube came as an optional factory upgrade. It's a decent tube but not worth $20 from the Maverick website. It can be purchased for much cheaper than twenty bucks. The bass is easily it's best feature. A wholesome bottom, the bass/mid bass images very well in the stage...seriously. There is a pleasant warmth from top to bottom although it is not as extended as the 1956 WE 396a. Imaging lacks a bit of focus, the sound stage isn't well layered, yet, there is still a sense of dimensionality.

1956 Western Electric 396a D getter: This tube excels when it comes to sound staging; excellent layering and separation or space between performers/instruments. The high frequencies are holographic and right in front of you while the the upper midrange was pushed a couple of feet back and the mid range was somewhere in between. Very fun to listen to. This tube portrays detriments that forced me to remove it from the DAC. There is a lack of sub bass and mid bass that can not be ignored. On the other hand, the mid range is screaming for attention. The mids are highlighted which forces me turn down the volume and leave it turned down because my ears are sensitive to the "loudness" of the mid range. I can see how this tube can be amazing on certain systems. Not in mine. Burn in was over 50 hours when this evaluation was made.

GE JG 5670WA: The bass is solid but not as strong as the 5670W. The sound staging is open and almost as good as the WE 396a. Detail and frequency extension at both extremes are just right; not too much and not too little. Tonality wise, this tube will sound a bit colored, specially in the mid range, if you're used to a dynamic tube as the Western Electric. The background seems to be blacker than both of the previous tubes giving a sense of depth and dimensionality. This tube moderately portrays the best features of my previous tubes. I found a keeper.

For anyone that has one of these DACs, upgrading the three op amps with dual discrete op amps from Sparkos Labs is a significant improvement.  I had the GE upgrade tube from the manufacturer and upgraded to a WE 396 and really didn't notice much difference, but the op amp upgrade was like getting a new component.