alright guys and girls. After rolling in opamp LT1364 and LM4562, I found that my right channel gone. So I do a little check up and found a broken wire. I can't find any of these info here, thus I'm on my own with a set of cheapo multimeter trying to figure out what's all the wiring in the D1. First let's see the internal.
Few things interest me here. But first I would like to stress that some of these info are not verified and any mod you try using the above info will be at your own risk, I will not be held of any responsibility if you damage ur D1 Also bear in mind that soldering work will void your D1 warranty.
1) As you can see from the internal shot, a very thin (looks cheap) set of wire was use for DAC output to the vol pot/input sel before going anywhere else. One of my wire break of from the connector after rolling opamps, it sure does easily break off. What I did for temp measure, is use "analog in (to tube)" yellow color wire to replace it. And I immediately notice improvement in the SQ, more separation, dynamic and airiness in the highs. (try with LF353 in the DAC, LM4562 in the hp amp). If you don't use the SS or tube out, you can try this.
On the other hand, if you use only the tube out (as Tube DAC output to external preamp), just unplug the yellow hp out wire jack(lower left) and plug directly to DAC out and you get similar by pass effect but better signal path (I haven't verify this)
2) Having found that the DAC out wire is not as good as the yellow one, may be Ryan should try to replace that with yellow color wire. I personally plan to get some mundrof wire to replace this. Also you can replace the stock wiring from the hp amp out to hp jack with better cable.
3) I was still wondering why D1 design do not feed tube out to the internal hp amp for better SQ? I try Windmill-Getter Raytheon output to pico amp, it sound so open and mid is lush even before proper break in of the tube. I was wondering could I solder some wire and feed the signal from the tube out jack and plug into the hp amp in jack (jack is the same as PC fan jack, should be easy to find)?
4) Back to Opamp rolling. These are just my observation. The 2 stock LF353 doesn't sound similar to my ear for sure. Initially I only roll the HP amp 353 to LM4562. AB the 2 LF353 in the DAC, one sound more dynamic and the other sound veil. I like the more dynamic one, which compliment well with layback/dark sound of LM4562. Later I roll out the DAC 353 with LT1364, and found out LT has better separation, more mid bass, more define bass. But it not as airy as 353. Likely due to LT haven't break in. The LT1364 sure is hot, I can't place my finger in it for more than a second.
5) last, wish to seek advice from some expert here, I plan to mod the caps to mundrof as well. Care to share some suggestion of what to replace other than the hp output caps at C61/C62?