Do all Passive preamps exhibit this trait

Hi Clio09, with TVCs its a different game and in that context I agree with you. My comments apply only to passive volume controls that are transformerless.

A properly designed TVC can, IMO, do better than the best PVCs; in fact I think that unless you have the very best in an active line stage, that a good TVC is going to be one of the better if not best alternatives.

Lack of dynamics hasn't been my experience with any of the passives I've owned:

Promitheus TVC
Sonic Euphoria (autoformers)
Bent TVC (S&B trannies)

In all of these cases, dynamics seemed explosive, not lethargic. The presentation also seemed airier and more detailed than actives in the same price range. I've heard the new Bent passive with Dave Slagle's autoformers and would say the same thing.

I don't doubt the calculations show:

passive controls traditionally limit dynamic contrasts and bass impact as you turn the volume down, due to the interaction between the cable, the input of the amp, and the control itself

but in practice, these shortcomings were minimal or inaudible in my system. This was especially true of the Sonic Euphoria and Bent with autoformers. Low level listening with these passives was a pleasure. They had a fullness at low volumes that seemed more natural and proportional than an active.

However, a back-to-back comparison of the Bent TVC and an Audible Mod3a indicated something was missing in the midbass area. A friend and I both agreed that the Mod3a was noticeably warmer in a good way. After a year of intense interest in passives, I've returned to an active, but I still believe a good autoformer-based passive will outperform most actives in the sub 1000 category.

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

Mingles, sure sounds like your experience is similar to mine, but keep in mind also the caveat 'properly designed' which I am careful to use. IMO, most of the active line stage technology you see today seriously trails behind amplifier and phono preamp technologies. I feel that this is because many line stage designers are not even aware that control of the interconnect cable is one of the goals/functions of the line section.

Being the ONLY person responding who owns and uses the Adcom GPF 750's active and passive in my system...
My other stuff: Forte' 4a amp, B&W 805s speakers (With B&W sand filled stands)Sony SCD777ES AudioResearch phono PH-2 (balanced out)Dual Golden one with a Shure V-15Vmr
Anyway, My experience is that the Adcom in passive mode is 'cleaner' but a bit thin when listening to stuff I want to sound 'full'
When in powered mode, the upper octave gets a bit grainier, the mids bloom a bit, along with the lows.. and the lows get boomier(muddied) , though not louder.
I would say (having owned the Adcom since it came out...) Is that the associated components are what give it the colorations. The adcom in passive is an excellent preamp. It passes what is put in. (cables here are a big deal) in dynamic (powered) mode, it is a decent preamp.
Jazz, Rock, and Classical, all have different needs. The system I have does what I want fairly well.
Also, I use a powerline conditioner. The Adcom is into the Monster 7000SS from an AVS2000. And my amp is from the wall via a adcom power conditioner that only has the amp plugged in.(the amp from the MC7000 is too thin but vary clear. straight from the wall, it is more even, but is not as clean, so the adcom conditioner is a compromise)
The sound from the pre changes with the various ways I had the items connected from the wall, and the power cords I used. The main difference was in the thinness/clarity vs bloom/loss of clarity.
I have only modest cables and powercords.