Passive Pre-amp: Improves overall sound quality??


Sam Tellig in Stereophile was all jazzed up about a line of "passive pre-amps" he received for review How does a passive pre-amp work?? Is it powered by wall AC?? What are some of the pros and cons of its operation within an audio system??
sunnyjim
While I'll agree with Sam's article about passive pre's I did have a chance to listen to that particular passive unit for several weeks and it was extremely good but I still preferred Steve McCormack's VRE-1b pre-amp and by a wide margin, which by the way only puts out 6dB of gain. There's an axcellent review that just came out here:
http://www.ultraaudio.com/index.php/equipment-menu/284-smc-audio-vre-1c-reference-preamplifier

(Dealer disclaimer)
Marebg, you forgot one of the most important things a great active is needed for.

- great sounding music from a stereo system

At least this has been my experience even when all the stars were aligned perfectly for a passive to shine.
Do you suppose that Sunnyjim is really a troll, recognizing that we haven't all gotten our fists bloodied over the passive vs active debate for at least a month?
Lets list what a preamp does:

1. source selection
2. voltage gain
3. attenuation
4. buffering (impedance matching)
5. tone control (older preamps,typically)

Let's get rid of #5 for now- passives don't have them, most good line stages don't either.

To that list we can add 'control (and limit) the effects of the interconnect. So:

1. source selection
2. voltage gain
3. attenuation
4. buffering (impedance matching)
5. control the effect of the interconnect cable.

The the latter 2 aspects are not served by any passive or transformer device. If you have ever heard the difference a cable can make, then you might appreciate that if the preamp is doing its job, the difference between a $100 cable and a $10,000 cable could be rendered inaudible. Now some people want to pay for the cable so that they can say that they did that, but if you are not one of those people you might consider that you can get the same or better performance without that $10,000 cable if your line stage is built with that ability in mind.

I find the colouration of uncontrolled cables to be unacceptable in any system. Sure it sounds transparent, but where is the body and impact? Not making it to the amplifier is the answer. To get around this problem people with passives will spend of lot of time and money sorting out the cable issues as best they can. So if you are thinking passive or TVC, keep in mind that the interconnect is the hidden and mandatory cost.
I am not sure if a good TVC needs a particular cable or not. For me, I kept using the existing cable. But the most important aspect of a TVC (passive), I learned was the "gain" aspect.
You have to be absolutely careful in selecting the amp (and speakers - which I consider secondary) that you will be using with the passive. I was looking for a very good amp which was highly sensitive. the lower the sensitivity number, the highly sensitive it would be. The Parasound that I have has a sensitivity of 1V for full power (250 Watts). There are other amps that are more sensitive than this amp - but they are all tubes, and I did not want to go that route. When I got the combo in place, it sounded better than the integrated I had in place. But when I moved to the new room and wanted to place the speakers 4 feet in front of the wall, I missed the bass and body.
It was only when I moved up to XLR, that I actually got the "body" of the music that I was missing. I have my speakers 4 feet from the front wall and 30" from side walls and find that I have a great bass. Honestly, it is a night-and-day difference in my system. I believe this is the body and impact that Atmasphere is talking about. But again, it was a "gain" issue. Most people whom I have interacted with before, use TVC with tube amps. So, gain is not an issue for them, even when they use RCA.
I would be more than eager to compare my TVC with the Parasound JC2 preamp to see what more an active preamp can do in the system. If at all I upgrade the TVC to a active preamp in future, it will be either this preamp or the newer version of JC2. But my next upgrade will surely be CDP/Transport with a balanced output, that will ensure much more gain in my system.