Do all Passive preamps exhibit this trait

Typically passive preamps do not exhibit this trait, but depending on the rest of your system you may have trouble finding what you are looking for. A good passive preamp should not add or subtract anything from the equation. However, impedance mismatches and cable issues could cause the problems you are describing.

In my experience I have preferred transformer or autoformer based passive preamps versus their resistive counterparts. The TVC/AVC passives tend to match up better in most systems. Impedance matching is important with passives. Just changing the setting on the volume control could impact the output impedance on the passive. Also, since we don't know the rest of your system there are a few things you should look for moving forward.

1. Your source has enough output to drive the passive (2V or better with low output impedance).

2. Your amp should have high input impedance (50k or better) and be sensitive (1V or less to drive it to full power).

3. Try to keep cable lengths short between the source and passive and passive and amp. This is more applicable to the resistive passives, but probably a good practice with any type.

If it were me, after determining if my system was passive friendly I'd try a TVC/AVC and see what happens. Lots out there to try that you can find used for good prices. Promitheus, Antique Sound Labs, and Sonic Euphoria come to mind.

Also try reading this:

http://www.stevens-billington.co.uk/page102.htm

One other thought, try the new Pass B1 unity gain buffer preamp. The buffer eliminates the impedance issues and the circuit does not have a gain stage. Sounded really good at RMAF when I heard it there.

If you don't want to pay the Pass dollars Audiogon member Rawsonte has been advertising a couple DIY versions here for great prices.

Ralph,

That was not my experience using the S&B transformers. My setting was about 12 o'clock and it was fine in my system. My amp was .8V sensitivity with high gain and 67k input impedance.

I do agree in principle with what you are saying and the data in the S&B link I provided bears this out. However, it appears that the data also supports that the changes in impedance due to the volume control setting are not that big a deal and I would have to agree based on my experience.

Ralph, glad we're on the same page with TVCs, although I trust your passive volume control option for the M-60s is well designed.

Mingles, my K&K TVC (S&Bs) outperformed my Cary SLP-98 ($3995) and Joule Electra LA-100 MkIII ($3750). I'd venture to say the Bent units in particular, either the S&B or Slagle models will outperform many preamps, both sub and over $1000.

Now Dave Slagle has come out with a manual DIY version using boards developed by John Chapman for a ridiculously low price. Just add a case and some RCAs and you're done. Even if you had someone build it for you it would still be a bargain.

See here:

http://www.audiogon.com/cgi-bin/cls.pl?preatran&1230319450&/Intact-Audio-Slagleformer-Modu