Purifi Class D: Junk?


So, from the previous thread about high-end class D the Purifi module was brought up. I decided to get a cheap example from VTV, a simple stereo unit with a single Purifi module and matching Hypex SMPS. Standard input buffer. I got it in yesterday. First impression wasn't what I was expecting: weak, congested dynamics is what stood out to me. I expected greater expression through my ProAc D30Rs. The other problems such as poor soundstage, thin / boring character, etc, I marked up to needing burn-in before evaluating. So it's been 24 hours, I would still expect to get at least the high control / damping of high end class D and dynamic power, but it's just not present.

Could it be an impedance mismatch? Other manufacturers selling the Purifi with their custom input buffers are reporting 47k Ohms. VTV doesn't say in the manual or on the site. I checked the Purifi data sheet which reports...2.2k Ohms on SE???? That can't be right?? That's absurdly low! Am I reading the right spec? My preamp has an output impedance of 230 Ohms. Can someone confirm that the stock Purifi has this ultra-low input impedance?
madavid0
Given the price of high end audio equipment, if you are doing 1K units a year, 3 year design, 3000 units, you could amortize the $100K design cost, at $33/unit additional.  Most audio companies would be best off contracting that out.  Hypex does their own, and I have seen some a company or two offering audio targeted switch mode supplies.
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I have to say that I am enjoying the sound from my DIY Purifi amps a lot more than the Nord NC500 amps I had last year. I don't know if this is because of my use of a large linear power supply in my DIY amps, the difference between the Purifi module and the Hypex module. the difference in input buffers, or other changes in my system. But these new amps are much more dynamic and engaging. 

I don't have the experience or knowledge that atmosphere or audio2design have, but based on my 45+ years experience as an audio enthusiast and tinkerer, a good power supply makes a huge difference in the sound quality of all audio electronics. I don't doubt that it's possible to achieve this with an SMPS. But either way, I think many (most?) class D amplifier companies are not making the effort and/or are not willing to increase their parts cost enough to deliver close to the full potential of what class D can offer.


Do the NC500 buffers work on the Purifi modules? That would be nice for a guy like me to try. Just swap 2 amp modules. Cable swap maybe?

Just wondering?

Regards