I got the new tubes that I mentioned above. They did what I was hoping for.
The sound signature has not changed, which is good. Is it any warmer? Hmm, I think it's not. Softer, yes.
But it did correct the bass, and now it doesn't sound like clapping bass or distorted.
With stock tubes, some songs were very strange and unpleasant, while other songs or genres were just great.
Nothing is lost now; it's a bit corrected, and that's great.
I am so curious now what TA-66 will bring to the table.
What's also interesting is that when I got TA-26S, I thought it sounded so different from anything I had.
Not long after, I bought my first electrostatic headphones and amp, and what a surprise that was.
It was completely different sounding from the rest, dynamic or planar headphones that I have.
And then...I was thinking that if any of the combos that I have could relate to electrostatic,
it would be TA-26S, especially when listening to HD800S. It's not that class, not even close, but it's a similar-sounding profile.
And that is...something to think about, too
I still haven't tried listening to jazz or classical music with it, but I think it has the potential to be great.
EDIT:
The day after... I am positive these tubes are better...and also dead silent. Of all Sennheisers I think it suits HD600 the best.
Not that others don't...but HD600 gets the most from this amp.
Emphasis on the bass that xDuoo has matches just nicely to HD600.
I am really surprised that this TA-26S had critics.
Still waiting for the TA-66
Cheers!