soundcheck's Purifi amplifier

Let's talk a bit about amplifiers. I owned numerous devices. Commercial and DIY. Jeff Rowland, Anaview Abletec, Hypex,  T-amps, SMSL and the list goes on and on. I tried many of those ebay Class-D modules. I tried all kind of power supplies (connex/hypex/linears, ...), I tried several full digital amps. and I compared these to even more amps owned by audiophile friends of mine. 

Oh dear. What a career. I swapped Class-D output transformers with Mundorf coils, replaced rectifiers, cabling, fuses connectors, power cables and the tweak list goes on and on.

And finally I got hooked up to a  Purifi Audio Eigentakt 1ET400A Stereo Eval1 amp integrated into a Ghent Audio case.

I am running this amp for more than a year by now. Puh. What a journey.

Spoiler alert:  This is the best amp I ever had - supplying me with almost "boringly" clean amplification. A so-called wire-with-gain. Everything that gets thrown at it will be displayed.  I simply can't find any amp specific mannerism. The numerous measurements and reviews out there confirm it. 

My old Hypex stuff as all my other (tweaked) amps performed worse. Period. My Abletec/Anaview AMS0100-2300 was IMO close (not close enough though). However. On performance/cost  the Anaview was and IMO would still be the better choice!
Whatsoever. There was simply no better amp then the Puriri in my system yet.

The next question one the table: What is/was done with the preamp-section or volume control!?!?
I did have a Jeff Rowland Pre in the past. I sold it quite a while ago. I was running several passive pres. And the probably best solution was a  Bent Audio Transformer potentiometer. 

The best of all preamp solution to me though is to use "No PreAmp at all". Since years I am hooking up my amps right to the DACs and make sure the amp gain structure matches the DAC output voltage and my speaker sensitivity. Levels and impedances should also comply to specs btw! A preamp and its cabling will add flaws. Always. That's basic physics. 

There's one caveat. At system turn-on or during DAC initialization turn-on pops might blow your speakers. Better look for a DAC that doesn't have that turn-on-pop problem. On well designed DACs the output stage gets muted at DAC init to avoid this behaviour.

However. You better make sure there's a proper system turn-on sequence in place. That lowers the risk substantially.

What's been the learning so far!?!? 

1. quality amps play not such a big role - not causing huge differences
   
2. I can get rid off preamps and HW VCs if
     1. I get an amp that mates/matches the DAC output  
     2. the amp gain level matches my speakers sensitivity
     3. I run a quality SW volume control
     4. I just run a single source 
     5. I make sure that the chain won't blow my speakers
3. fully integrated solutions (DAC and AMP, powerDAC, full digital amps) are IMO still the best solution for the future. These amps are reducing DAC>amp interface related flaws even further.  ;)

Let's get a bit more specific about my setup. 

My latest amp is a Purifi Eigentakt Eval1 amp  housed in a Ghent Audio case. I also use the Ghent Audio harness.  PS is Hypex SMPS1200. Power cable is a ViaBlue X-40. I run the amp differential hooked up to Neutrik plugs + Voodoo solid core silver wires.

I did have to tweak the Ghent Audio case. I removed that IMO "awful" Ghent Audio power switch and connector section as well as the internal power cabling and attached the Viablue right to the Hypex SMPS. This noticeably did improve the perceived sound quality. I run a central mains switch at one place (power distribution). All my DC rails (DAC and RPi) are controlled via relays and wifi. That allows for a proper turn-on and turn-off sequence. The AC rails get a slight cleansing by using an iFi AC purifier.  I also disconnected the Ghent LED board recently. I don't need it. I also have the speaker cables soldered to the Purifi board. There's nothing better and cheaper than a nice silver-tin soldering joint.

The Purifi Eval 1 comes with the generic Purifi input buffer stage. The Purifi buffer stage allows for choosing different  pre-gain levels. That's great. I run it at 0dB - no pre-gain - setting. Over at the ASR review  you can see the 0dB setting is the best performing setting.  And IMO you can also hear it. To me it sounds cleaner.  As I mentioned before, such a setting has to match your DAC and speaker sensitivity levels.  YMMD.

Audiophonics offers a similar Purifi based amp. It comes with a custom input buffer though. I think the Audiophonics offering is a pretty fair commercial solution. Actually you can find several 3PP buffer offerings for the 1ET400A modules out there. I had a look at them and couldn't find any advantage over my generic Eval1 buffers - which essentially get (partially) bypassed @0dB anyhow.
Perhaps there are also better power supply options out there. To be honest. For me it's good enough the way it is for the time being. Optimizations on my upstream gear and front-end (DAC/RPi) still cause a lot more differences on perceived sound quality then the tweaking on the amp side. 

Now. The source.

I was running my seriously tweaked Gustard A18 differentially straight into the Purifi amp. This was and IMO still is a great combo. Now I am doing it with the Allo Katana. It works nicely. The Katana base output voltage is a bit lower than the Gustard. This still works quite well. 

Anything else to report?

The amp is IMO quite expensive. I'd say: It's a rather good "audiophile" value for the money though. However. My Abletec Anaview ALC0180-2300 modules were also performing great and that at $180. That keeps bugging me. 

However. The Purifi amp is a great performer. For sure it's able to challenge the best stuff out there.

I wouldn't call the Purifi my final amp though. Because I think a fully integrated DAC+amp or PowerDac/Full digital amp solution or a digital active speaker solution has the potential to beat a chain build from seperate devices. 

I also would like to see the volume control on the high power side. A voltage level controlled amp output.  I think TI had a solution for it on it's full digital amps. EC-Designs is offering a 4W PowerDAC-S solution that would cover a lot of aspects on my wishlist. Price and power constraints make it a NoGo for me.

Keep in mind to choose your amplifier based on your system topology and requirements. Making your buying-decision just by looking at the standalone (lab-) performance of such a device might hit you on the wrong foot... ...if you happen to run a 98db/W speaker you probably better have a look at e.g. the above mentioned EC Designs solution.

Enjoy.

PS:

...while still dreaming about affordable and highest quality full-digital amps...
What I don't understand is to see Peter Lyngdorf from Tact listed as co-founder in the Purifi team . Lyngdorf is one of the full-digital amp pioneers. Tact had a real good rep in the full-digital amp arena. And now he seems to support a full-analog Purifi amp again. Hmmh. That must have been a big step back for Lyngdorf. Perhaps - fingers crossed - one day Purifi will go the all-digital route. For sure they have the right team onboard for getting it done.