My Tube-01 Preamp arrived today, with the GE JAN 5654W tubes. It's such a cute little thing.
Currently letting it burn in and settle. (It's amusing to listen to, as the signature will change after 10 minutes, making any EQ attempts feeble. For example, the bass just got stronger during my play of "Hotel California", and I just decided to turn off all EQ.)
The unit by default comes with 6N1 tubes, but I opted for the upgraded tubes for $20 more. (what a racket tube sellers have) I opted for the upgraded military spec tubes in hopes for longer endurance and clear signal. These sound great. My first note is that the output from the G6 has a touch of dryness (typical of odd order SS harmonics) which the preamp has removed. That alone makes the upgrade worth it. The timbre of instruments and vocals have also improved, becoming more of what they should sound like. Very reminiscent of the signature of my HD580, those lush, rich vocals, but with the added strengths of the Tesla drivers.
The gain output can go stronger than typical 2V RMS, so I'm finding I have to keep adjusting the preamp output as the tubes break in, and synergize with the Asgard 3 to improve dynamics and impact. I had a VERY impressive TV show watching of "FBI Most Wanted" with some great effects impact, Very authoritative.
These tubes are known for clarity and smoothness, and they are. Smexy smooth, wets the sound just enough, and adds a touch of sweetness. Overall a great improvement. No comment about warmness since I'm only about 2 hours into this, but so far the DT-1990 sound great with the new Dekoni pads and no EQ. If they don't change much more, I'll do a small subbass boost (about 2-3dB), and that'll be it. I love the fact that some tunes that I loved on the HD580, and did not sound as good on the DT-1990 now sound as involving as they once did. Joy!
PS - Tube glow is so mesmerizing!
PPS - When adjusting the preamp gain, if I go too far, I find the mids start to get pushed forward in a bad way, and things get a little shouty. So far, 2:00 seems to be ideal for impact, bass, and maintaining balance.