I have now constructed a passive preamp that has neither a Dact, and is obviously not a GK-1. However, this project got underway with both a Dact and GK-1 in mind. The purpose was/is to make a passive pre with the idea of eventually incorporating it into my GK-1, which is far far away at the moment.
After a lot of postings here, and a lot of study in various places on the net, I made a passive with a Goldpoint Shunt 20K, with a Vishay S102 as the I/O resistor and Dale RN60 shunt resistors, and an Elma selector switch. I've now modified the wiring to make the main input direct into the attenuator and just use the selector switch for secondary inputs.
I decided on the shunt as I liked the purity of just 2 resistors in the signal path, and it was a lot simpler than a full ladder.
Goldpoint seemed to be the only one with real shunt pc boards. Michael Percy has a good selection of kits, especially if one goes the ladder route, or wishes a 48 position attenuator. Dact is series only.
I chose a 20K attenuator as that was the closest to the 22K of the GK-1.
The Sound: I think the insertion of this passive into the system and the retiring of the BAT preamp qualifies as near a "fundamental difference" to the music, rather than a small tweak to the sound.
A big "veil" that I never knew existed was lifted making the sound much cleaner and clearer. Details came out that were previously hidden.
This was as big a difference as when I got my AKSA 55 mono twins going nearly a year ago.
At the moment, the sound of everything is so good, I really wonder if I will want to try to combine this with my GK-1 when the time comes. Also, not sure how the shunt attenuator with the slightly variable impedance, will integrate into the GK-1.
According to the placette audio website, to get the fullest out of an attenuator, even the shunt resistors need to be of the same high quality as the series resistor. But the high cost of S102's would make that quite expensive, essentially cost prohibitive without winning the lottery. However, eventually may look into using some Vishay VSH resistors, much lower cost, in some of the most used positions.
Thanks to everyone here who contributed information - Larry, Mal and others.
