DirectStream Sr/Jr as a Preamp


#1

I’ll preface this question in that I’m still fairly new to understanding all the myriad nuances in the audiophile world…

Given that DS can work as a preamp, what benefit is there going to a standalone preamp if that preamp is going to remain SS? Are there users here using their DS as a preamp with a standalone poweramp? I have an integrated amp now (Hegel H360) but I wonder if I should get rid of it now that I have DSJr and look at getting a stand alone power amp.

All my listening is through digital mediums and at the moment am not interested in going down the rabbit hole of vinyl!

-Matthew


#2

There is pretty even mix of those who use a preamp and those who don’t. Personally I don’t. I found that with my (previous) Audio Research LS-25 the sound was better without it. Of course the need for analog inputs is a big determinant, but that is not a problem for you. There have been several discussions on this topic, I found one from several months ago … Click. Try searching in the DS forum for others.


#3

The DS DAC straight into my BHK Stereo 250 sounded really good. For some reason adding in a BHK Pre amp opened up new levels detail and provided additional dynamics in my all digital system. All that said, you could start with a DS DAC direct to your power amp. The pair will sound better than adding all but a few pre amps in the chain.


#4

I think most DACs benefit from a gain stage between it and the amp. Then there’s the whole question of if that should also be flavored/colored.


#5

My DS Sr runs balanced direct into a fully balanced 500wpc solid state power amp. The sensitivity of the system is such that I can hear the DAC’s noise floor when nothing is playing and the room is quiet. (It’s not the amp’s noise floor – the white noise vanishes completely when I engage the DAC’s 20dB output attenuator or switch the DAC off.) And my goodness can it play loud if I want it to. Most modern recordings with little or no headroom are house-fillingly loud with the DAC volume set to 50.

So no: I do not need a “gain stage” between the DS and my amp.

My amp’s input impedance is 50k-ohms, which is not far shy of the BHK Pre’s 66k for balanced. The DS DAC output impedance is almost as low as the BHK Pre’s. So no: I do not need a “buffer” to better match my source and amp electrically.

Interestingly, I find that engaging the DS output attenuator distinctly degrades the audio quality in my very highly resolving system, despite the reduction in background noise. It could be as simple as a slight roll off at the top end but something becomes lost in terms of fine detail, the decay, the imaging and soundstage etc.

Given that I’m at the point where something as trivial as a resistor shunt to ground causes audible degradation in a minimalist system that’s producing some of the best audio quality I’ve ever heard (and I’ve heard a decent amount), it’s extremely hard to imagine that adding an entire pre-amplifier’s worth of additional circuitry and another set of interconnects would deliver a purer signal. Purity is what I’m after – tone, timbre, colour, ambience etc must come to me in the recording itself.

As with everything else, it comes down to what you like and what you want from your system. A pre-amp can solve problems with impedance and gain matching, it can offer flexibility with multiple analogue sources, or it can provide some kind of additional tone control or harmonic sweetening. If - as for me - none of those are relevant, you can happily live without a pre-amplifier between your DAC and your power amp.


#6

Gain staging (in the context I’m talking about) has relatively little to do with whether you have enough gain going to your amp to make it suitably loud. My Junior going directly into my amp gets loud enough, though I would be running it at 50-60 on the volume control, which (though it is equipped with lots of bit headroom) is a sonic disadvantage vs. running the DAC at its nominal level of 100 (some say 99). This may be the reason you can hear the DACs noise floor - you’re turning it halfway up, and then amplifying that signal 2x vs. running at 100 and amping it half as much. But of course you don’t have that option without a pre.

In the context of audio recording it is important to optimize levels at all stages, otherwise you are either adding to the noise floor or not fully taking advantage of the sonic benefits of a given device, such as a mic preamp.


#7
dvorak said Given that I'm at the point where something as trivial as a resistor shunt to ground causes audible degradation in a minimalist system that's producing some of the best audio quality I've ever heard (and I've heard a decent amount), it's extremely hard to imagine that adding an entire pre-amplifier's worth of additional circuitry and another set of interconnects would deliver a purer signal. Purity is what I'm after – tone, timbre, colour, ambience etc must come to me in the recording itself.
This is conceptually persuasive and logical. But, annoyingly, a good preamp can sound better than not having it in the chain. I am fully in your camp where timbrel purity, texture and microdynamics are by far the most important.

If you are willing to spend the money and make space for it, it is worth trying a preamp. Either your suspicion will be correct and it sounds no better, or you will discover a way to improve your system once again.

PS Audio is delighted to send you one on approval . . .


#8
Elk said
But, annoyingly, a good preamp can sound better than not having it in the chain.
So true - I was also in this 'minimalist chain' way of thinking too. And then I heard a great tube preamp in between the DS and power amp and it changed everything. I can't speak for anyone else but as much I REALLY tried to not like what I was hearing, with a tube preamp my ears ended up overruling my brain.

#9
Mi2016 said . . . I REALLY tried to not like what I was hearing . . .
4_gif

#10
Mi2016 said
Elk said

But, annoyingly, a good preamp can sound better than not having it in the chain.

So true - I was also in this ‘minimalist chain’ way of thinking too. And then I heard a great tube preamp in between the DS and power amp and it changed everything. I can’t speak for anyone else but as much I REALLY tried to not like what I was hearing, with a tube preamp my ears ended up overruling my brain.


You aren’t alone. I have always loved how the DirectStream sounded through the Audio Research Reference 5SE even if it did mask some of the details and initial attack. But the trade offs in soundstage and midrange lushness was just too good.

And then I put in the BHK Signature Preamp - which restored the transients, the attack while still having that amazing soundstage and midrange lushness.

It’s one of the reasons I’d like to see reviewers put the BHK Pre against the industry benchmarks for preamps like the Ayre and Audio Research.

It is really that good.


#11

I was most sceptical when the BHK preamp was announced… Thinking that P S Audio had to build a preamp to match their power amplifiers - and borne out of necessity… The mantra; “There is no preamp like no preamp” And why bother anyway - my system performed effortlessly, musical to the nth with the DS connected directly to the BHK-300s; …and I was very happy and contented with my system configured this way so why change the status quo … Well, when I heard the BHK preamp in my system - I was gob-smacked; … because it wasn’t just a mere hifi change - it was massive, a huge musical improvement ! Everything Bascom and Paul said it would be !


#12

I guess I’ll have to find an opportunity to have a listen so I can speak from experience rather than just theory – at least when it comes to the BHK Pre. I don’t think PS Audio offers free trials outside the USA, so my opportunity to attempt this comparison may be limited.


#13
dvorak said

My amp’s input impedance is 50k-ohms, which is not far shy of the BHK Pre’s 66k for balanced. The DS DAC output impedance is almost as low as the BHK Pre’s. So no: I do not need a “buffer” to better match my source and amp electrically.


Hi Dvorak,

I was under the impression that the input impedance on the power amp should be at a least 10x higher than the output impedance on the preamp, ideally 20x…

The DSJr’s specs are Output Impedance: 100/200ohms (SE/Bal?)

Perhaps I’m getting confused here.

I’m looking at Pass Labs offerings which have an input impedance of 30/20 Kohms (SE/Bal) so on paper these should have no compatibility uses.


#14

You do seem confused, but I know that feeling well :slight_smile:

My power amp’s input impedance is 50,000 Ohms. My DAC’s output impedance is 200 Ohms. That’s a ratio of 250:1. At 1V signal level there would be roughly 0.02 milliamps of current requirement from the DAC. I think it’ll be OK with that.