That is a lot of questions
Q on -6db switch
When the -6db switch is selected on the 01J, it adds another 10K resistor on the input. It’s helpful to reduce gain if going into an amp that to sensitive. I use it between source and a preamp. In the end I don’t want any gain since I use the preamp for volume. If I deselect the -6db switch, I need to set the volume on the 01J to 11 o’clock. If I turn on the -6db switch, I need to set the volume on the 01J to 1 o’clock. I end up just not using it. I sometimes will play with the volume on the 01J if the source is particularly weak or strong which can happen with different sources. I made custom VU meters so I can see if the signal is weak or strong. But for the most part, 11 o’clock serves me well.
But if you are asking about the 01 vs 01J, the 01J has advantages over the 01 outside the -6db switch. It has a lot of similarities, but it is a different circuit design. This is translated from Japanese since all the marketing is there. It states, “the biggest attraction of the product is that the plate voltage is raised by the DC-DC boost circuit and draws out the original performance of the vacuum tube.” One of the complaints of these units is they don’t utilize the tube as much as it could. The 01J does that better than the 01.
Also here is a site in Japan that describes the advantages. Use chrome or a mobile browser that can translate to English
https://ameblo.jp/itazuraltuko/entry-12501746027.html
Q on the power supply
The device does not need a lot of current. Someone did a test, and I don’t think it even pulled an amp. See page 77. More amps matters if you are using the same power supply for more than one 12v device. The device only draws what it needs. As for voltage, the device can take more than 12V. It depends on the tube, but 13.3v seemed to be an ideal set point. I got an Astron RS-4A, it’s linear, has smoothing capacitors, and can be set between 12v and 14v. Unlike the amp capacity of a power supply, if the voltage is set to high, it will destroy the components. I would make sure that the TeraDak you are considering has way to set the voltage. It has more than enough amps. You may need to splice a different adapter if does not fit. The 01 and 01J uses a 5.5mm x 2.1mm tip.
Q on the tubes.
Dr ear loves the Philips Holland E95. I would love to try them too but have never been able to find them. Mullards are supposed to be very warm. Frankly most of the good tubes will have an effect that we are looking for. For me the Voskhod 6ZH1P-EV has been outstanding. So electric and punchy on the low end.
I also heard that matching is less important on preamps, but I do try to find them matched. I would think that a mismatch would produce a different level that would affect imaging. Don’t know enough but I just do since they are easy to get matched.
Here is a nice listing on tubes for our device. It was for the little dot but similar in what it does
https://www.head-fi.org/threads/little-dot-tube-amps-vacuum-tube-rolling-guide.563884/
Q on the polarity
Yes, you would just switch the red + and black – on each speaker. But I tried it and can’t hear the difference. Can’t hurt to try. But if you have a subwoofer, you will have to invert that as well. Thats trickier depending on your hookup.
Here is a test for absolute polarity. You tell me if you can hear it.
https://www.audiocheck.net/blindtests_abspolarity.php
