Adding a pre amp

[Mustu]

Hello guys.

 

At the moment I have a PS Audio Direct stream DAC with a JEFF ROWLAND 625S2 power amp and use SOTM set of 3. I am thinking to add the PS audio BKH pre amp. 

 

Can anyone shed some light on this?  

Cheers

[coot]

I highly recommend adding a pre. I did so acoupla months ago. It improved SQ by "fleshing out", providing a fuller, richer body over all.  You will like the improvement.

[gmgraves]

1 hour ago, mustafakaiser said:

Hello guys.

 

At the moment I have a PS Audio Direct stream DAC with a JEFF ROWLAND 625S2 power amp and use SOTM set of 3. I am thinking to add the PS audio BKH pre amp. 

 

Can anyone shed some light on this?  

Cheers

I assume that DAC has a level control? Do you have any other sound sources other than that DAC? An FM Tuner maybe, a turntable perhaps, or something else like a cassette deck or R-to-R tape recorder? If the DAC is your only source, and if it has it's own level control, then I say save your money. A preamp's job is two-fold. It is there to provide enough inputs to allow the user to switch between sound sources, and it allows for a bit of gain for sources that might have lower outputs than others. Some preamps even have "trim-pots" for each high-level input so that they all can be equalized to give the same loudness at the same at the same setting on the main volume control. Finally (and this has become rarer and rarer recently), preamps can provide the proper amplification and RIAA equalization to to accept a phonograph cartridge. 

 

Taken as a whole, the above description seems to show that if your DAC is you're only source, you don't need a preamp (even though you might want one, but that's a different subject). Another thing to consider is that most all preamps are active devices with transistor, tube, or IC gain stages in them. every active circuit that your audio signal passes through adds distortion and noise. Distortion and noise that your system does not have as of now. It's probably not much noise and distortion, but it will change the sound of your system. How much and in what way is impossible to predetermine, and you may or may not like the change. If the added functionality of a preamp is needed, then the tradeoff between the extra noise and distortion added by the extra gain stages and the added capability afforded by the addition of a preamp into your system is probably worth it. 

[diecaster]

https://www.youtube.com/watch?v=HHl8F9amyY4

[Blake]

From a theoretical perspective, it doesn't seem to make sense, but like Bascom King (in the video posted above by diecaster), my system (as it has changed and evolved over the years) always sounds better with an active preamp in the chain. I have never had a system combination where it sounded better without a pre.  I really wanted to get rid of the preamp and use those funds for other purposes, but couldn't.

 

If you search around audio review sites and fora, Bascom is not alone in his view.  Plenty of professional reviewers and consumers have come to a similar conclusion (system dependent, of course).  Having said that, preferences and system synergy can flip things the other way and you will also find lots of proponents of going without a pre.  All you can do is experiment in your system and see what you prefer.   

[cjf]

Adding a PreAmp to a system vrs DAC direct is the perfect example of when Theory and Reality dont line up..IMO.

 

The theory of course being that the presence of a Pre in the chain does nothing but add more noise/distortion resulting in worse sound. Most folks who claim this are also the same folks who made such a comparison using a less then stellar Pre in the first place. You cant drop less than  $5K on a Pre and expect it to be doing you any favors given the quality of the DAC's today.

 

I would even go as far to say that dropping $5-10K on a Pre is probably the minimum requirement otherwise DAC direct may very well be better assuming the DAC is of very high quality and the volume control method deployed while using this configuration is one that is pure software at 64bit or Analog based within the DAC itself, which is somewhat rare, but not impossible to find if you look hard enough.

 

Like others have said, I've never found a DAC direct setup that could beat the sound of one with a very good PreAmp in place. Not yet at least

[Panelhead]

  If a preamp improves the sound quality of a dac with variable volume the dac output stage is the issue. 

  Another feature of a preamp is impedance matching. High input impedance and low output impedance. There are a lot of variables. 

  I have a lot of preamps in the attic. Croft,  Audible Illusions , and a diy using 6080 tubes. Also  several solid state, and a few passive. All actually do a great job at input selection, low coloration, and ability to drive an amplifier. Even the passive models work well when connected to an amp with high input impedance and driven by a low output impedance source.

  But the three dacs I use regularity sound best straight into an amplifier. Maybe you just have to listen for yourself and decide.

[tdimler]

On 2/12/2018 at 1:50 PM, mustafakaiser said:

Hello guys.

 

At the moment I have a PS Audio Direct stream DAC with a JEFF ROWLAND 625S2 power amp and use SOTM set of 3. I am thinking to add the PS audio BKH pre amp. 

 

Can anyone shed some light on this?  

Cheers

 

I also have a 625 S2 and run directly to it from my Mytek Manhattan II DAC which has an excellent built in digital and analog pre-amp.  I have been in the same boat as you, wondering if a dedicated pre-amp would significantly improve SQ.  I recently had the chance to try two outstanding pre-amps......both of which sounded excellent, and did a bit to smooth things out and were perhaps a bit more fleshy.  I don't think you could call the sound better though, just different.  As a fun piece of gear, I'd love to have kept either of them, but given the eye watering cost of top shelf pre-amps I could never tell someone it was worth it if they were expecting a leap in sonics.

 

FWIW, Jeff Rowland prefers going direct from his Aeris DAC into a power amp for a single source digital system.  I was surprised to see the absence of a pre-amp in his listening room.  This should be a testament to the quality of volume control in well designed DACs.

TD

[rickca]

1 minute ago, tdimler said:

Jeff Rowland prefers going direct from his Aeris DAC into a power amp for a single source digital system.

That's exactly what I do with my Aeris and 625 S2.  My dealer still wants to sell me a Corus ... and the ultracapacitor PS.

[diecaster]

I am with BHK (watch YouTube video I linked above). A quality active preamp, especially a tube preamp, makes a real positive difference. The sound is more musical and dynamic. 

[Ralf11]

I like my pre-amp - it gives me tubey goodness, and allows me to switch to an FM Tuner

[barrows]

With that set up I would never add a preamp period.  The only thing you can possibly hope to achieve by adding a preamp is to color the sound with additional distortion and noise.

[barrows]

On 2/12/2018 at 1:42 PM, coot said:

I highly recommend adding a pre. I did so acoupla months ago. It improved SQ by "fleshing out", providing a fuller, richer body over all.  You will like the improvement.

This will not be the result with his set up.

[Ralf11]

adding a preamp may color the sound with additional euphonic distortion

 

- what do you want??

 

you can kiss your  -140 dB noise floor goodbye too...

[diecaster]

3 hours ago, barrows said:

This will not be the result with his set up.

 

I disagree. While the DirectStream preamp is quite good, it is no match for a quality active tube preamp. Please watch the BHK video I provided a link to.....I have a DirectStream and have tried it with and without a quality active preamp. I have a quality active preamp in front of my amp.....

[barrows]

1 hour ago, diecaster said:

 

I disagree. While the DirectStream preamp is quite good, it is no match for a quality active tube preamp. Please watch the BHK video I provided a link to.....I have a DirectStream and have tried it with and without a quality active preamp. I have a quality active preamp in front of my amp.....

There is no such thing as a "direct stream preamp"...  I hate hearing this kind of statement as it suggests that one has to add something to a DAC to drive an amplifier directly.  A DAC has an output stage, which is no different from what a preamp has, an output stage (in general).

In this system case we have a DAC which has a transformer coupled output, driving an amplifier which is very easy to drive, which has a transformer coupled input.  While some have suggested that putting a preamp between an amp and DAC can result in better sound by the ability of the preamp to act as a filter for RF energy from the DAC, in this case, we already have two very effective RF filters: transformers at both the receiving and transmitting ends.

All tubes can do is add distortion and noise, you might "like" the distortion and noise, there is nothing wrong with that, but it is not accurate, or high fidelity, it is only added distortion and noise which is not part of the music recording.

[TubeLover]

1 hour ago, diecaster said:

 

I disagree. While the DirectStream preamp is quite good, it is no match for a quality active tube preamp. Please watch the BHK video I provided a link to.....I have a DirectStream and have tried it with and without a quality active preamp. I have a quality active preamp in front of my amp.....

Not only do I agree, but I can back it up. A good friend of mine had the PS Audio Direct Stream DAC in his system for the past three years up until a couple months ago. He tried it direct to a whole series of amps, and each time, things improved dramatically when he added his PrimaLuna Dialogue Premium preamp (highly recommended, and  steal for the money) into the mix. The consistencies in sound without the DAC were sound that was lean, too much towards clinical,  and lacking texture and depth. Adding the preamp, in virtually each case improved the sonic signature of his system, adding depth, richness, a believable degree of warmth that hugely improved the midrange, and highs that extended believably and effortlessly. We spent many, many hours verifying this, as well as bringing in other audiophiles in the area to verify what we kept finding. And the findings were always consistent.

 

Now, will I say that there is no way that a DAC, with a volume control, connecting directly to amplifiers can be as good, as having a really good preamp in the system? No, but be prepared to layout out BIG dollars for that DAC. I bring this up because over the past few months, my friend has found a DAC that is actually producing better sound from his system connected to any of the three amplifiers that he owns. However, that DAC cost him well over $15k! 

 

JC

[Panelhead]

8 hours ago, Ralf11 said:

I like my pre-amp - it gives me tubey goodness, and allows me to switch to an FM Tuner

  My Day Sequerra FM tuners have AES output along with balanced analog. I prefer the AES through a dac. But Richard Sequerra tells me that the analog output is the same. 

  He is most likely correct. FM, FM-HD, AM, AM-HD are lower resolution than most other digital sources.

[diecaster]

21 minutes ago, TubeLover said:

Not only do I agree, but I can back it up. A good friend of mine had the PS Audio Direct Stream DAC in his system for the past three years up until a couple months ago. He tried it direct to a whole series of amps, and each time, things improved dramatically when he added his PrimaLuna Dialogue Premium preamp (highly recommended, and  steal for the money) into the mix. The consistencies in sound without the DAC were sound that was lean, too much towards clinical,  and lacking texture and depth. Adding the preamp, in virtually each case improved the sonic signature of his system, adding depth, richness, a believable degree of warmth that hugely improved the midrange, and highs that extended believably and effortlessly. We spent many, many hours verifying this, as well as bringing in other audiophiles in the area to verify what we kept finding. And the findings were always consistent.

 

Now, will I say that there is no way that a DAC, with a volume control, connecting directly to amplifiers can be as good, as having a really good preamp in the system? No, but be prepared to layout out BIG dollars for that DAC. I bring this up because over the past few months, my friend has found a DAC that is actually producing better sound from his system connected to any of the three amplifiers that he owns. However, that DAC cost him well over $15k! 

 

JC

 

Thank you! BHK and Paul McGowan, the CEO of PS Audio, prefer using an active tube preamp versus using only the "purely passive output stage" with digital volume control of the DirectStream.

[diecaster]

1 hour ago, barrows said:

There is no such thing as a "direct stream preamp"...  I hate hearing this kind of statement as it suggests that one has to add something to a DAC to drive an amplifier directly.  A DAC has an output stage, which is no different from what a preamp has, an output stage (in general).

In this system case we have a DAC which has a transformer coupled output, driving an amplifier which is very easy to drive, which has a transformer coupled input.  While some have suggested that putting a preamp between an amp and DAC can result in better sound by the ability of the preamp to act as a filter for RF energy from the DAC, in this case, we already have two very effective RF filters: transformers at both the receiving and transmitting ends.

All tubes can do is add distortion and noise, you might "like" the distortion and noise, there is nothing wrong with that, but it is not accurate, or high fidelity, it is only added distortion and noise which is not part of the music recording.

 

Hate? You are arguing semantics. Of course the DirectStream does not have a preamp built in. Of course it has an output stage. Every DAC does. Heck, most preamps today are actually line stages. Should we mention that every time someone uses imprecise terms?

 

As far as what active preamps, tube-based or not, do? Yes, in in theory you are correct. Yet, to this day, active preamps are used and preferred by a huge number of audio enthusiasts. As @cjf said, this  "is the perfect example of when Theory and Reality dont line up". As a purist, I would like to believe that a passive preamp or no preamp at all would sound better than an active preamp. In my 40 years plus of experience, that has not been the case.

[sandyk]

1 hour ago, barrows said:

we already have two very effective RF filters: transformers at both the receiving and transmitting ends.

 

 And they can't add distortion, introduce phase changes, or premature high frequency roll off, especially with high res 24/192 or DSD ?  

My own DIY Class A Preamp for example , is only -3dB at 1.5MHZ.

[GUTB]

So, to address the usual rounds of misinformation on this topic: pre-amps are required.

 

The output stage of a DAC is not a pre-amp. It will just take the small signal out of the D/A stage and generate a 1-4v for transmission down a cable. Most DS-type DACs will offer a digital volume control which is adjusting the signal down (attenuation) that is passed into the output stage. As we've discussed and analyzed in the past, digital attenuation is trash and should be avoided. Some DACs, notably the Myteks, have the option of using low-quality analog control (via chip) in addition to digital attenuation. The output stage still has to be good -- the preamp won't fix it -- but to realize the best sound you still need the preamp.

 

An active, discrete class A gain stage (triodes, FETs, etc) with serious voltage amplification and power supply capability is required for good sound. Every single experienced audiophile knows this. The less experienced have a perception that a line stage is just for volume control, and if it's just for volume control you don't need it if you can control volume digitally -- either through digital attenuation or via software before the DAC.

 

The noise question. Preamps deal with small signals, and they have a higher noise floor than DACs and often times more than power amps. Don't worry about the noise floor, worry about the quality of your sound. If you want rich harmonic textures, full bass, a good soundstage and dynamics, you want a preamp. If you're a non-audiophile who doesn't place a high value on sound quality you may be fine without one.

[barrows]

19 minutes ago, sandyk said:

 And they can't add distortion, introduce phase changes, or premature high frequency roll off, especially with high res 24/192 or DSD ?  

I think you are misunderstanding me.  The output stage of the DAC and the input stage of the amplifier do not ADD distortion as they are necessary.  By inserting an additional component (a preamplifier) between them one is then adding (unnecessary) distortion.

The distortion/noise of the amplifier and DAC are what they are, the additional distortion/noise of the preamp is an additional distortion/noise.

[firedog]

27 minutes ago, diecaster said:

As @cjf said, this  "is the perfect example of when Theory and Reality dont line up". As a purist, I would like to believe that a passive preamp or no preamp at all would sound better than an active preamp.

Or it means that the reality is that most people have been conditioned to think colored sound is the more accurate. Maybe if they had listened for years to systems without a separate pre, they'd think a system with a pre sounds inaccurate and colored. 

[barrows]

26 minutes ago, GUTB said:

The output stage of a DAC is not a pre-amp. It will just take the small signal out of the D/A stage and generate a 1-4v for transmission down a cable. Most DS-type DACs will offer a digital volume control which is adjusting the signal down (attenuation) that is passed into the output stage. As we've discussed and analyzed in the past, digital attenuation is trash and should be avoided. Some DACs, notably the Myteks, have the option of using low-quality analog control (via chip) in addition to digital attenuation. The output stage still has to be good -- the preamp won't fix it -- but to realize the best sound you still need the preamp.

The above factually in error entirely.  The output stage of a DAC and the output stage of a preamp are the same thing: line level, low impedance drive circuits capable of driving a cable to a high impedance load.  In many cases the circuits are identical.  There are some DACs with very weak output stages, and such DACs may not be capable of driving some amplifiers adequately, but these pairings are rare.

 

Additionally, digital attenuation, as long as it is used within its capabilities (without using too much attenuation), is transparent, whereas analog attenuation is not.

Please stop spreading myths and presenting them as if they are factual. 

 

If you honestly believe that digital attenuation is problematic (within its capabilities) then I guess you only listen to all analog recordings as well?  After all, almost all digital recordings are mixed using digital attenuation, I suppose you also believe that all digital recordings are trash as well.