Have Passive Preamps Finally Come of Age?


Back in the late 90s (eons ago) I tried a variety of passive preamps (PPs). The most musical was an autoformer, but back then my system was not balanced. For the last decade I have been using active preamps, both tube and solid state, but finding a quality balanced preamp under $4K is damn near impossible. Enter the Parasound P5 (2.1), which in addition to having balanced I/Os, it has a separate bass management circuit (MSRP $1095), and I was hoping it would provide better control over the built in class D plates incorporated into my 2 SVS powered subs, whose volume controls are STUPIDLY sensitive: when barely cracked from zero they overwhelm. Alas, no bueno. 

Recently i watched a PS Audio YT video that was emphatic about NOT connecting powered subs with interconnects; instead he recommends speaker cables piggybacked off the main systems amp/s. I had a spare set of DIY flat copper cables, and was shocked how much better they sounded, but doing so did not change the  volume control problem and unfortunately this id not bypass the SVS amps whose class D chips are now ancient. Thinking there could be an impedance problem led me to revisit PPs.

I sold my P5 and was using the XLR outs from my Oppo 105 (upgraded power supply and IEC/wiring to the power supply) direct to my Emerald Physics 100.2SEs (class D). The noise floor dropped tremendously, allowing me a much better view into the music. My Core Power Technologies 1800 PLC had more than a little to do with this, but...  

Days of PP research later, I came across LDRs, which seem like the ultimate PP option, but XLR versions are ~ $2K and up, with the Tortuga coming in at $2700, seems like a true SOTA bargain, just not in my current budget. Scouring the' for sale' sites I came across a Hattor XLR (MSRP $995) which was in my price range. Hattor's www had links to 2 reviews both were extremely positive: one used it in combination with a class D amp. Bingo! I snapped it up.

It arrived late yesterday, although Hattor's www pictures look awesome, they do not compare to seeing and touching it. The metal carrying case was an indication of the designer's dedication. This is an etremely well made piece of kit, but how does it sound? Alas it came with no manual and Hattor's site does not have a PDF. How hard can it be to hook up? Well, after a couple scary minutes, I discovered that it would not light up until I connected the 105. 

Stone cold, the first thing that shocked me was a further reduction in noise floor and an incredibly wide and deep sound stage, but as can be expected, it was dry. Fingers crossed, in about a half hour I began to be rewarded with texture as well. Tis only got better as the night wore on

I hope somebody chimes in with their Tortuga experience, or any other high quality PP information.that goes under the reporting radar. 
tweak1
If a passive has a buffer stage, is it still a passive?


No! If the signal goes through an active circuit it’s an active preamp with no gain.

Cheers George
I think TVCs are the way to go passively and don't experience the loss of dynamics, etc. that resistor-based passives bring. I compared my Music First to several active, tube preamps and it was the champ. 
I think TVCs are the way to go passively and don't experience the loss of dynamics,
TVC's are also great, but they do have their own colouration if you don't mind that, as that poor weak source signal has to go through a "mile" of very thin transformer wire winding and back out again, they are not as transparent to the source as other passives.
Plus never get one with "gain" stay with unity, as they do have a tenancy to "ring" from the test we've seen.

Cheers George  
Reading back through, I have a couple comments

1. I believe NPass is speaking to a perfect electronic interface world, which would necessitate building ones system around a PP, as opposed to trying to insert one into a active preamp system

2.. A quality PP, such as the Hattor, is a high powered microscope, exposing whether there is/are problems/issues elsewhere in the chain. 

I feel that my Emerald Physics amps are the next step in my progression,  I am close to pulling the trigger on a Nord Two SE Power Amp (newest class D tech), and .I  have the next model Emerald Physics Speakers (3.0) with cap upgrade and WireWorld internal wiring on the way (I think, as they were supposed to be hear almost 2 weeks ago) 
1. I believe NPass is speaking to a perfect electronic interface world, which would necessitate building ones system around a PP, as opposed to trying to insert one into a active preamp system

I believe it does, and that "perfect electronic interface" is available in systems much much more than not.

1: If the source has more output voltage than the amp has input sensitivity to give full output. This is maybe in 100% of cases.
(I have yet to see a source with less output voltage than the amp needs input voltage to make it clip) 

2: The ratio of output impedance to input impedance, of the source to passive and from the passive to the amps,  are both 1:10 ratio or more, this also would be in at least 90% of cases. 

Then you have what you call,  that "perfect electronic interface" for a passive to work as it should, which is getting the source signal to the amps in the most transparent, undistorted, uncoloured, unhindered way.

Cheers George