Any thoughts on removing a preamp from your system

In my second system (the one in the vertical cabinets in my system photos), I have 6 sources:

1) phono
2) Squeezebox Touch
3) DVD
4) tuner
5) VHS tape
6) cable box

The last 4 feed into an old Radio Shack/Realistic unpowered "passive" 4 source switching box gadget I have had for years. This was a $20-$30 gadget as I recall many years back.

Then the "passive" source switching device runs into tape in on an old NAD 7020 receiver that I use for pre-amp only that feeds the TAD Hibachi monoblocks that drive my smaller OHM speakers and my Stax phones.

SB Touch runs direct into the NADs aux input and phono to NAD phono input.

This works quite well. None of the sources I am feeding into the passive Realistic box are SOTA certainly, but the performance is quite suitable. I have heard these devices running directly as well in the past, and if there is a difference, it does not seem to matter much.

That makes me think a true good quality passive pre-amp with a good quality volume control might work quite well. Definitely something worth considering if needed.

Whenever Al chimes in, i just skip to the bottom of his post and try to understand his conclusion. I thought I was somewhat smart until I started coming around here, haha!

I really love my Lightspeed Attenuator. It definately removed that last layer of haze I had at the time. I think it has incredible transparency and dynamics and it was $500. I think you'd have to spend 3 to 4 times that much to even begin to make an improvement, probably at the cost of some transparency.

"I admire Al's technical knowledge as well but what do you expect him to say? "

A purely technical analysis/comparison as only a good EE might concoct.

Understanding the technology is always the key to making good decisions. Of course, you never know for sure how it will sound until you hear it in your situation, but I always like to go in as technically informed as possible.

My own assessment is that if the mating from a volt and impedance perspective looks good on paper, a simple high quality circuit behind it is all that is needed for optimal results. The there is the technology behind the volume control, a different and perhaps more complex story, but not Rocket science still.

Of course optimal results technically does not assure a winner soundwise in the end, given all the other things that factor into any good sound, but its a darn good place to start.

Mapman, thank you kindly for the nice words.

I haven't ever experimented with any kind of passive preamp, or with direct drive from a source component, because in my case it would pretty much be a non-starter functionally. I have five sources, having widely differing output impedances and levels; and my preamp supplies outputs to three destinations (I could readily do without one of them, the record out to my tape deck, but I definitely need outputs to my headphone amp (which I drive from a second tape out) and of course to my power amp). Also, the cable length from preamp to power amp is long enough to be something of a concern with many passives.

Regarding your question about why some people who've tried both approaches report better results with actives, even if cable lengths, cable capacitances, and impedances are all ostensibly suitable for a passive, I would speculate that one reason is that discerning listeners having resolving systems can hear effects attributable to those parameters to a degree that is somewhat greater than would be expected on the basis of conventional analysis.

A speculative and hypothetical example, to illustrate my point: If the combination of cable capacitance and the output impedance of a passive preamp (which will depend on the setting of its volume control as well as on the output impedance of the source component which drives it) results in a bandwidth of say 50 or 100 kHz, that would ostensibly seem likely to be sufficient. But perhaps in combination with bandwidth limitations elsewhere in the system the result might be phase shifts in the audible upper treble region that are sufficient to produce time domain misalignment of those frequencies relative to lower frequencies, to a degree that may be perceptible under some circumstances. In other words, more bandwidth margin may be necessary in some circumstances than is commonly recognized.

I'd imagine also that a contributing factor in some cases is along the lines of the point George has made in a number of threads, that active circuitry may be introducing colorations that are euphonic. Not that there's **necessarily** anything wrong with that, IMO.

Another reason may derive from the combination of the facts that it seems clear that not all cable effects are technically explainable or predictable, and passive preamps (or at least resistance-based passive preamps) can be expected to magnify cable effects as a consequence of their relatively high impedance levels.

The point that was made earlier about sonic degradations being introduced by the parts in a passive preamp probably also has some validity in many cases, but FWIW my own instinct is that if those parts are chosen to a high standard interface effects are likely to be more significant. Others may disagree.

And in situations where digital volume controls in source components are being used in lieu of having any preamp, presumably "bit-stripping" would be a factor in some cases.

So I think that the answer to your question of "why" is multi-faceted. And I certainly wouldn't rule out that in at least a few cases the "why" might simply be user error in configuring the application.

A lot of experienced based opinions have already been expressed in this thread, from many whose opinions I have great respect for. As you said initially, there is no single right and wrong answer, that will be optimal in all circumstances. But FWIW mine own instinct (based, as I said, on having no experience with passives) is that Brownsfan's particularly nuanced post rings especially true.

Best,
-- Al