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
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
jaytor
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
Not saying which are better Class-D modules but yes!! my NC500’s took a giant leap also, with big linear power supplies, made me realize smp’s no matter how well designed are not very good for audio.
And then there was another jump again going direct in, with no input buffer, so long as your source has the gain, and <50ohm output impedance output stage/buffer.

Cheers George
They are basically compatible. The NC500 has a clip output which the Purifi board does not. The NC500 recommended op amp supplies are +/-15v where as the Purifi module recommends +/- 12V, but the Purifi max rating for this supply is +/- 20v, so you should be ok swapping in the Purifi module in an amp designed for the NC500. 
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Thanks jaytor, I'll check it out. Got to be worth a listen..

Regards