Good call out. You’re right that you cannot “reduce bit depth” when the number of bits are on/off (DSD being 1 bit). But, bit density does get altered and that still reduces dynamic range. I have no idea what kind of dynamic range the DS is capable of so its very possible its well beyond any “damage” we’d hear by reducing that range to provide volume control.
It still changes the bit stream so I still don’t like it 
Appreciate identifying the PCM vs. DSD issue in my post though.
No, this is similarly untrue.
No information is lost with the DSD’s volume control - be it bit depth, resolution - anything.
The internal volume control keeps all of the incoming information: every bit of the input affects the output of the DAC for any volume level. There is no rounding, dither or other information trimming. The output is a full 50 bits wide.
Summary: no data loss whatsoever.
A good pre-amp doesn’t improve the sound quality, it just does not degrade it as much as a lesser quality pre-amp.
Thanks, I already have a P15. It was my first purchase after doing some exploratory surgery of the electrical in my home. I am doing a post on it soon. If people knew how miswired new homes can be they would not sleep well. The P15 cured all that. Bringing a brand new line from the outside would have been costly, take a lot of work and not solve some of the electrical problems I’ll talk about in the post. The sonic benefits, as you say, were very evident.
Preamp is the heart of my system. Everything thing is colored by the preamp…and I like it…a lot.
If you already have a DS DAC, BHK 250 and a P15, the BHK Preamp is certainly the next logical step in the journey to more dynamics, more detail and better sound stage.
For reference I started with a DS DAC & PWT, switched Clase amps for a BHK 250, added a P10, added a BHK preamp, switched the PWT for a DMP; switched the BHK 250 for 300s and finally switched the P10 for a P20.
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That’s in practice especially but not only untrue in terms of dynamics!
However I understand that just from theory and without practical experience with such a case, all this sound difficult to follow.
If a good preamp do not degrade the sound as much, then no preamp should not degrade the sound at all. We now know that is not the case as even Bascom King could not explain how putting in a BHK preamp inproves the sound. I believe the signature of the preamp is incorporated into the overall sound, so if a preamp sounds full bodied and with incredible soundstage, then you hear some of that also in the final sound.
I don’t know if it’s amusing or sad that people are telling @psalvet to get a BHK pre-amp when it is about three times his remaining budget and his actual practical problem is getting his vinyl through his system, which is easily done with an A/D converter.
As @Elk has explained, PSA DAC’s have a superb volume control and I used one straight into an amp for some years. This is what PSA says about it (see the Features tab at DirectStream DAC Factory Refreshed – PS Audio):
### Resolution perfect volume and balance controls
Designer Smith perfected a 100% bit-perfect volume and balance control that’s built into DirectStream, enabling users to control the output level when feeding directly into a power amplifier or preamplifier. That the volume control is completely bit-perfect means there is no loss of resolution for any volume setting, a feature unique amongst the majority of DACS in the world today. The ability to eliminate the preamplifier in the system without any resolution loss is a major benefit to DirectStream’s outstanding musical performance.
So PSA’s website says their DAC eliminate the preamplifier in the system without any resolution loss is a major benefit. If that’s the case, why not use it? It’s one of the reasons I bought a PSA DAC.
Whether or not the a BHK pre-amp makes music more enjoyable, and I’ve yet to hear an explanation why, is really irrelevant given @psalvet is not going to buy one and can’t even get to borrow one. That may change in the future, but for the time being all he seems to need is a converter.
Can’t answer all the OPs questions, but yeah the DSS sounds way better with the BHK Preamp OR a high end tube preamp like an LTA ZOTL. They just open up the sound stage and add needed presence (harmonics) in such a nice way. I wouldn’t bother with a SS preamp, or an overly colored one.
Where it works is if the preamp is high quality enough to retain the original audio quality, and add harmonics and flavor from the tubes, but not to an extant that anything is noticeably changed or lost. It just makes the soundstage and space more audible, textures more tangible, and colors richer.
And yeah, screw converting vinyl to digital unless you convert it to DSD and/or have a really, really good ADC (Mytek Brooklyn ADC, Playback Designs Pinot). Good ADCs are maybe a little cheaper than high end preamps because many are built for the pro audio market, but you still get what you pay for. There are ALOT of ADCs and DACs I would never use for vinyl.
Well first, the DSS straight to a sensitive amp is noisy as hell unless you use the -20db “DAC Level” output pad and/or unbalanced outputs, where you lose a little sound quality with each. Second, lots of gear like the higher output voltage of the BHK preamp vs the low voltage of the DSS. And third, tubes sound good, and those little bit of extra harmonics make the soundstage and texture more apparent. The BHK preamp can do this without any apparent lose of resolution, which makes for a net benefit in sound quality.
Steven, it is true that my practical problem is which will produce the better sonics affordably, digitizing the phono signal for the DSD DAC or sending it straight to a preamp, as well as which of either device might be the best fit for my speakers (Focal Electra 1038be).
It’s good to know there are folks doing digitizing who are quite happy with the results. It’s also good to know that no one who tried the BHK or another good preamp had disappointing outcomes.
It’s clear that going forward will take a considerable amount of research, trial and time. I love to learn so I’ve got my work cut out for me, and while I learn I’ll continue enjoying the music.
I have a lot of leads to follow. Than you all!
An interesting and informative debate - everyone’s a winner 
@IanB52 's comment suggests that the BHK pre-amp is adding some distortion, which does not interest me, and I have no interest in having tubes in my line level amplification (been there, but I actually have a tube phono amp on order).
I presume you are using balanced outputs from your DAC to your BHK250. I was using a PSA PWD Mk2 DAC balanced directly into another brand of power amplifier and got no noise at all. The DSD DAC does have a slightly lower voltage output. If the DSD/BHK250 direct combination does produce noise as @IanB52 suggests, and given what PSA says on its website about the DSD DAC’s volume control, and would cost $6,000 to fix with a pre-amp, I would consider the unit faulty and get in touch with PSA direct.
When I was going direct to my amp with my PSA DAC, I dealt with the vinyl another way. I had an amp with switchable balanced and unbalanced inputs, so I used a phono amplifier which had volume control and plugged that directly into the amplifier’s RCA sockets. I doubt the voltage was particularly high.
It’s not so much that I put my vinyl through A/D, it’s built in to quite a lot of systems ad there is no loss of audio quality. Some purists want analogue to stay analogue the whole way, but I’m not so dogmatic. In fact I’m not dogmatic at all.
There are clearly lots of DSD/BHK pre/BHK power owners who want you to follow them, even though it’s not in your budget and not the immediate issue. Obviously you will want to try it in the future.
I’m not quite happy with my vinyl going through A/D conversion, I’m totally relaxed about it and that it has no effect on the sound at all. I use an all-in-one unit that has phono amplification inside, but have recently chosen to use a an external phono amplifier. I’m using a solid state one at the moment, have a tube one on order.
I did briefly have a pre-amp. I wanted it to switch between by PSA DAC and vinyl and to attenuate, so I got a product that did exactly that, totally passive. It cost me $800.
I’ve had this discussion with at least a half dozen non DSS owners: 1 bit conversion creates a high noise floor. If you have a sensitive amplifier+speakers and use balanced interconnects, you will hear noise unless you use the output pad (which exists for a reason). There is absolutely nothing wrong my DAC, or any other one that does this. PWD MkII is a totally different design.
It seems like you have your own experience with tubes, but the discussion about “distortion” is misleading because we aren’t talking about a guitar fuzz pedal, or even anything that changes the attack or decay in noticeable or detrimental ways. We are talking about a subtle increase in harmonics, and whatever other mysterious coloration a tube input stage does. Some may prefer the duller and dryer tone of the direct DAC output, but I wouldn’t be without the preamp using the DSS.
I also have to disagree with your assessment for A/D conversion. I’ve owned or worked with around 20 different ADCs ranging from a few hundred bucks per channel, to $5000 per channel, and not a single one of them is perfectly transparent to the source at any bit depth or sample rate. With cheap converters and low sample rates there is no benefit whatsoever of sticking with vinyl and not just downloading the music from iTunes unless you really want to hear surface noise because any fidelity advantage from analog will be lost. For those that do care about it, if you want digitized records to sound like records, at least get good conversion, use DSD, or the highest PCM sample rate you can.
If you look at the first line of @psalvet 's post opening this thread, he said:
So I don’t think it matters if you’ve spoken to 1,000 other people, @psalvet is clearly delighted with feeding his DSD DAC directly into a BHK250. He never mentions or suggests a problem with noise, so I don’t know why you raised it. Plus PSA explicitly state on their website the DSD DAC (and the PWD DAC) are designed to be fed straight into a power amp, so is that untrue?
With regard to digitising vinyl, the main reason why systems like Linn Exakt, Devialet Expert, miniDSP, Dspeaker, and Trinnov (in both pro and consumer audio) use A/D is because it allows various forms of DSP, such as room correction, speaker matching etc. It has proven popular and successful. Our system works in 24/192 PCM and with a good pick-up and clean and static-free records (we wet clean) we get no audible surface noise, pops or clicks.
Not that anybody would do this but I wonder what the subjective listening results would be if a second BHK preamp was added in series with the first one.
Would the sound quality increase yet again, remain the same, or be degraded?
To address the subject of this thread, IMO adding a quality pre-amp (BHK in my case) clearly DOES improve sound quality.
That seems to be the view of the overwhelming majority of people who have responded also.
Define “quality” as increasing connection with the music, soundstage etc. etc. and a BHK pre improves it (i am told, and happy to believe).
Define “quality” as presenting the recorded electrical “wiggles” as accurately as possible (not necessarily the same as representing what was being recorded i.e. as if in the room with the instruments) then maybe not.
Seems to me this is the debate that is being played out here.
My own experience is that the right preamp definitely improves the SQ. I started out using the Stellar stack (GCD & M700). When I added the Schiit Freya as a dedicated preamp, the sound improved with better sense of dimension and took some edges off the Stellar GCD that could be fatiguing at times. I kept the Freya when I upgraded to the DSD Sr and BHK250, and my system still worked better with the Freya in the chain vs. DSD-direct-to-BHK250. Once I upgraded again by scoring a used BHK Pre, things improved even further (fill in the blank here with whatever audiophile cliché).