Purifi Class D: Junk?

@clustrocasual That's very interesting. If the Weiss is that good perhaps I'll hold off on returning it. How did you replace the cabling? Including the Molex connector cables?

I did not replace the Molex from the hypex power unit to the amp module, but its on my list. I would have to source the right cabling for this.

I did remove the Molex that connects to the IEC inlet and soldered the DPS directly to that board. I used the Furutech pure-copper connector clips for all other points, and soldered the interconnect from the XLR inlet to the board.

I plan to do a write up with pictures once I'm done with some final testing in a couple weeks. I did each part one at a time so I could hear differences, and with Furutech's notorious 300hr burn in, its taken me a few months. I don't change anything unless I hear a clear improvement. 

But the first thing I did was test the op-amps with basic OFC cabling and the Weiss really opened my eyes. (or is it the Purifi opened my eyes because the Weiss is transparent?).

If they are using the OEM Hypex boards as input boards it is crap. It is VTV’s fault.

???????  What are you talking about?  You can buy from VTV several different input boards......the Hypex OEM, the Purifi board, the custom VTV input board that allows all kinds of different op amps to be tried and also a custom VTV tube input board that also allows different op amps.

I had a pair of Nord Hypex NC500 monoblocks a couple years ago and was kind of disappointed with the sound  quality. These amps came with input buffer boards that supported the Sparkos and Sonic Imagery discrete op amps, and I tried them both. I preferred the warmer, smoother sound of the Sparkos in the system I had then, but not by much. The Sonic Imagery opamps offered noticeably more detail, but were more sterile sounding.

These amps replaced a Krell FPB-300 which had died for the second time and I decided it was time to sell it for parts (which I now kind of regret), and they really weren't a good substitute. Granted they cost WAY less and were a lot easier to deal with (both weight and power consumption) but they didn't work for me. 

I ended up selling them and replacing them with a Parasound JC-5 which I was much happier with. That was close to 2 years ago. I have since completely changed my system (although I still have the JC5) and have really gotten into DIY. After building a pair of FirstWatt F5 turbo monoblocks and a pair of Neurochrome chip-amp monoblocks, I decided to give class D another try. 

I recently completed a pair of Purifi-based monoblocks. But instead of using the typical Hypex SMPS, I built them with a large linear power supply, similar to what you'd expect to find in a high-end class AB amp (1500VA shielded transformer with ~200,000uF of Nichicon filter caps). As a first round, I decided to use the Neurochrome input buffers which are a well-engineered op-amp design.

I plan to experiment with other designs including discrete op-amps and fully discrete in the future, but with this relatively simple and cost effective buffer, these amps sound quite nice. I'm sure there is some "pride of my own build" bias  influencing my perspective, but I have to say that I was not that impressed with my FirstWatt F5 Turbo build. The Purifi amps are better in just about every way (more dynamic, much more detail, quieter background, sweeter midrange, better soundstage, WAY less heat). 

You can see a couple of photos on my system page. https://systems.audiogon.com/systems/8726

I'm thinking about trying an input buffer using the Weiss OP2-BP op amps next. I've heard good things about them, and it would be interested to compare them to a high quality conventional op-amp implementation.