Lots of passive preamp questions

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First, here is some background info for my setup now. My system consists of
two sources
1. Art Dio Dac: right now 7 volts at 220 ohm out impedance, also experimenting with modified to 2.3 volts
2. vcr: seems pretty loud, I want it to be significantly quieter than music level
ASL Wave 8 monos: 8wpc, 100k in impedance at 500mv sensitivity
passive preamp
-dual mono 100k audio taper log Radio Shack pots
-2 22.1 k resistors in parallel
-cheap 30 gauge wire
-dpdt switch
-cheap phono plugs
- Sound Dynamics RTS3 speakers (89 db efficiency)

result: Dio at 7 volts and vcr basically have no vol. control; starts in very abruptly and very small change results in very loud vol. change

What I'm trying to do:
-upgrade my passive preamp with better parts
-switch to a stereo pot
-make the volume control work better so that I have a smooth volume curve

For a passive preamp, would I be better off keeping the Dio's output at 7 volts and 220 ohms? There are well-documented mods that change some resistor values around to lower the output to around 2.3 volts, and I assume that the output impedance must also change, so does it go up or down. I thought I heard it was best to keep the output impedance of the source as low as possible.

I am also wondering about minimum attenuation and the amount of voltage necessary to drive the amps to maximum volume. I don’t think I am quite getting this idea right, but is there some minimum amount of voltage or current that the amp needs to be driven best? The amp says it has an input impedance of 100k ohms at 500mv sensitivity, and I’d like to get the most power out of the amps possible because my speakers are only 89db efficiency.

For best accuracy, it seems like a linear pot is a better bet than a log pot. But a linear pot does not follow the logarithmic volume change that we need to have gradual volume increases? So, if I’m using a linear pot, I need to use the law faking design and maintain the 6.66 to 1 ratio of pot to resistor?

Since linear pots seem to be the best, is the law-faking configuration necessary in order to achieve a smooth, natural volume control? What if I used a 10k pot? It doesn’t seem that a 1.5k resistor would be enough?

Does it matter if I remove the Teflon sleeving from the wire and what silver wire is recommended (where do I get it)?

Does the quality of dpdt switches vary? I have some hum, and I think I have good solder joints, so I’m thinking it’s either the uninsulated wire or the switch.

Finally, how exactly does the shunt principle work?

I would also appreciate recommendations on what stereo pot, resistors, silver wire, and switch I should get.
ASL is Antique Sound Labs in China? 8 watts so it is a SE? OK... what little help this might be, I don't have a passive preamp but I have built a couple of amps. I don't get anywhere close to the voltage you are getting and what I use are 1 meg pots on the amp chassis between the input RCA and the driver tube. I like to use a pot per channel so I can balance the sides since it is damn near impossible to have each channel exactly the same because of tolerances and how difficult it is to have tubes matched close enough together. Try grounding the chassis of the passive to your earth ground for the hum. Get some speakers that are more efficiant and if the 30 gauge is solid use 6 strands per pos/neg and do a french braid and you will have good cables. 2 strands per pos/neg and some plated copper RCA plugs and you will have good interconnects. If the 30 guage is stranded throw it out and if you are still interested in making your own cables and interconnects get a spool of magnet wire and braid that. Braiding provides better bandwidth. I find silver bright, and I like tubes....so no silver for me. Silver plated copper seems crazy since they conduct differently. If your wire isn't going to touch anything then you can remove the teflon sleeving.
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