Best Preamp - NO preamp... (?)

Ami,

I am also using my PS Direct Stream sort of direct. However, I have my Direct Stream first going to the BSG QOL and then to my Pass Labs Amp.

RE: What is "better"? that is something I can't argue with. If you like the specific distortion or the coloration that a component introduces, then by all means, go for it. I am on the search for "Hi-Fi" - transparency and not coloration. I am of the opinion that if you need to add a preamp to make up for your speaker's deficiencies, you should be looking for better speakers.

Less parts does not necessarily mean better sound. If it did we would all be using the same minimal all-in-one system.  Reproducing recorded music is more complicated than that.

However, if you enjoy  the sound of your system without a preamp, that's what's right for you.

They don’t have enough gain, so they need an active pre to help the signal along.

We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.

Is impedance matching an issue? Passive volume controls do have to make a trade-off between input impedance and output impedance. If the input impedance is high, making the input to the volume control easy for the source to drive, then the output impedance is also high, possibly creating difficulty with the input impedance of the power amplifier. And vice versa: If your amplifier prefers low source impedance, then your signal source might have to look at low impedance in the volume control.

This suggests the possibility of using a high quality buffer in conjunction with a volume control. A buffer is still an active circuit using tubes or transistors, but it has no voltage gain – it only interposes itself to make a low impedance into a high impedance, or vice versa.

If you put a buffer in front of a volume control, the control’s low impedance looks like high impedance. If you put a buffer after a volume control, it makes the output impedance much lower. You can put buffers before and after a volume control if you want.

The thing here is to try to make a buffer that is very neutral. Given the simple task, it’s pretty easy to construct simple buffers with very low distortion and noise and very wide bandwidth, all without negative feedback.

Link: https://www.passdiy.com/project/preamplifiers/b1-buffer-preamp

Other manufacturers have also found the no-gain to low-gain approach to work well, such as Steve McCormack who originally offered no-gain or +6dB options on his highly regarded VRE-1 preamp, which is basically a very high quality buffered circuit.  The +6dB option is standard on his current version of the VRE-1 with this relatively low-level of gain resulting from high quality output transformers he uses, and not the active circuitry.   Steve has found the power supply to be very important to the quality of sound of the buffered preamps he has designed.  

My personal preamp is a no-gain, buffered unit that was custom built by Steve McCormack and is very similar to his early VRE-1 preamp.  It works well with every amplifier I have used and sounds better than the over-20 highly regarded preamps that have paraded through my system over the years. Below is an excerpt from a 1995 interview with Steve where he was discussing his thoughts at the time on passives and buffering.  A link to the full article follows.

The sonic performance of the finished product, called the Line Drive, fulfilled all of the original design goals. It was characterized by the exceptional transparency and natural musicality which are now recognized as classic passive features when the preamplifier is properly designed and manufactured, yet rarely heard from other types of components.

With further experimentation, I discovered that the very best performance of my design came from running it with a high input impedance (20 kOhm or higher), high gain power amplifier. This too is characteristic of all passive units. The amplifier's high input impedance prevents loading effects while the high gain assures ample capability to drive loudspeakers to an appropriate volume level. Only extremely low loudspeaker sensitivity combined with low gain amplifiers present a problem for attaining high volume levels. Again, this combination of factors is rarely present in the real world.

While investigating early reports of "insufficient" volume, I found that people simply were not turning the volume control far enough to achieve the levels they wanted. Following the lessons they had learned about not turning up the volume of active preamplifiers too much as a precaution against system damage, these individuals were setting their controls too low. Since passive line-level preamplifiers have unity gain (1X), there is no reason not to turn the volume all the way up if that is required.

Please understand that I have nothing against active circuits, and I assume the same is true of other creators of passive designs. I build active units for applications where they are appropriate, such as phono preamplification. However, I prefer the passive path in some other applications because of the exceptional transparency and natural musicality possible through this approach.

During the latter years of the original Line Drive's seven year tenure, I worked with design refinements in preparation for releasing its successor. These experiments confirmed most of my earlier conclusions, but they also led me to appreciate the advantages of offering a buffered output in addition to the passive output. I had resisted that option for a while because the buffer circuits I knew had a negative effect on sonic performance. It was during the development of the Active Line Drive ALD-1 preamplifier that I designed a special buffer circuit that was based on a simple complimentary FET pair, but which required a very high quality power supply to make it work properly.

This was the first electronic circuit I had worked with that complimented the passive circuit and did not compromise sound quality. It allows the use of any length of cable between the preamplifier and power amplifier. Adding the buffered circuit brings the opportunity to enjoy the sonic benefits of minimalist preamplification to all systems.

Link:http://hometheaterhifi.com/volume_2_1/passive.html

• "We don’t always build our systems from whole cloth where we might have the opportunity to find a set of components with no interface issues: a preamp is a good thing to have on hand for the cases where other factors like gain mismatch or cable length or… get in the way of a well balanced system." - 
  

“There are two issues that come to mind: gain (which has already been mentioned) and the other is cable capacitance.

With respect to gain, there’s a “best” sensitivity of amp to use with the DS direct: you need enough headroom to have dynamic music (even on your louder tracks) but also enough sensitivity that you aren’t using the volume control far from 100 a lot of the time. Obviously if your music collection has tracks that are significantly different in loudness or dynamic range or if the amp isn’t sensitive enough or is way too sensitive you’ll probably want a preamp.
With cables that have too high of a capacitance there are FR response issues with almost any source. With most sources high capacitance implies a high frequency rolloff, but at times the transformer output of the DS can interact with cable capacitance to add a little high frequency boost. In an already existent system that already has high capacitance cables but is otherwise balanced changing from some other DAC to a DS may make quite a difference in the very top of the audio band. Either a rolloff or a boost of the highs could be beneficial in some setups, but in general, average to lower capacitance cables will be better with the DS or you’ll need a preamp to drive/buffer a higher capacitance or long run cables after the DS.
My counter argument to the minimalist point of view is that “Why should you expect a $6000 preamp in a $6000 DAC for free?” We don’t always build our systems from whole cloth where we might have the opportunity to find a set of components with no interface issues: a preamp is a good thing to have on hand for the cases where other factors like gain mismatch or cable length or… get in the way of a well balanced system.
Given a particular amp the DS could be designed so that you probably wouldn’t want a preamp – and similarly given the DS an amp could be designed so you probably don’t want a preamp, but in real life, as all things in audiophile land, you’ll need to listen for yourself to different setups and make up your own mind.”

Given the choice, I always prefer the sound of my system with an active preamplifier—the passive approach seems to me sorely lacking in drive by comparison—so I didn't try using the DirectStream to directly drive any of my amps.

Since the DS's analog output is variable, it can be used to drive an amplifier directly rather than running the signal through a preamp. Like most people who've compared a high-quality active preamp with a passive controller, I've found active preamps to be superior, particularly in dynamics. But the DS is different: its output level is controlled in the digital, not the analog domain, and Ted Smith, lead designer of the DS, claims that using the DS's variable output to drive an amp directly results in no loss of resolution. In fact, this is what PSA recommends for optimal sound quality.

Listening at matched levels through my Convergent Audio Technology SL-1 Renaissance preamp vs direct connection, I went back and forth at least a half-dozen times, trying to decide which was better—which should give you an idea of how close the sounds were. The sound through the CAT was a bit warmer, which was welcome with voices. The direct connection to the MC275LE resulted in even more finely defined detail, but perhaps veered slightly in the "clinical" direction. Overall, I preferred the connection through the preamp, but it was a close thing. The CAT is one of the best preamps around; pitted against a lesser preamp, the direct connection would likely be the winner.

That’s the quintessential description for the sound of the Antileon EVO, too. There’s a sense of weight, power, dominance and uncompromising authority to music when played via this amplifier. And it’s not just about the bass either. It’s about overall dynamics that approach reality (yes, rest of gear permitting…) with explosive contrasts. This last came through even more outwardly when I connected George Stantscheff’s Lightspeed Attenuator quad-matched LDR passive. The Lightspeed does no harm. It’s as clear a conduit to the musical content from your source as you’re going to get, provided all impedance parameters are optimal, and without hindering dynamic expression in any way, shape or form.

And if his source (AMR CD-77.1) had a volume control of it’s own, it would have sounded even better to him direct.

ami OP
Hi George,
I'm very impressed with your candor:

@ alfa 100

We strongly recommend that you use your Wadia 521 Decoding Computer connected directly to your power amplifier. Even if you purchased your Wadia 521 Decoding Computer with the intention of connecting it to your preamplifier, we suggest that you try direct connection to your amplifier. Many listeners are surprised by the improvement in performance over even the most expensive preamplifiers.

Optimizing the Output Level Best performance is obtained when operating the Wadia Volume Control near the top of its range. If needed, the maximum output level of your Wadia 521 Decoding Computer can be adjusted to match the overall sensitivity of your system so that the critical listening will take place with the volume control operating in near the top of its range.
The maximum output level of the Wadia 521 Decoding Computer is adjustable by means of a set of internal switches. The Wadia 521 Decoding Computer is factory set to accommodate the most common range of system sensitivity. If you find that your typical volume level during critical listening is below 65 on the volume display, it will be advantageous to use a different setting. To change the output level, consult your dealer.