Anyone Recently Change to Class D power?

@jaytor ,Thanks for posting the details. Yes, I did check out the amp on your system page. You have a fantastic room. Amazing that the Purifi competes with the JC5. I would think the JC5 is a detail monster, knowing what the A21 can do. For me the JC5 would be the logical upgrade. But I am reading a lot of positive reviews on the Purifi modules. Only 1 joker keeps complaining that they don't double the power when going down for 8->4->2 ohms. I don't know if that is even needed, The JC5 does not do that.
Do you think that the Purifi can comfortable drive a speaker that dips to 2 ohms? Hence let me ask another stupid question - why use linear power supply instead of the switching power supply?I have seen your other creations. I don't know how you do it - but to me those components looks professional grade. Especially that Purifi amp. Keep it up!

@milpai - thanks for the kind words. 

Most class D amps are built with a switch mode power supply because they are a lot cheaper, lighter and smaller, so the overall amp can be a lot less expensive for a given power output. Modern class D amps have lots of negative feedback, so the power supply rejection ratio is quite high and with the simple distortion measurements that are typically used, they measure just fine. But that doesn't mean they are going to sound as good. 

Over the years (45 yrs as an audio enthusiast) I have found that a good power supply with plenty of current reserves has more impact on the sound quality than perhaps anything else in an audio circuit. 

A large linear power supply can provide much more current reserves and not introduce lots of high frequency noise that has to be filtered out or removed using feedback. I have not A/B compared a SMPS supply against a large linear supply with the Purifi module, but almost all high-end amps, including class D amps, use a linear supply.

On top of all that, I wanted to add my personal touch to the amps, and I'm a lot more comfortable building a linear supply than trying my hand at an SMPS. I didn't want to just drop a pre-assembled module in the box. 

And I'm quite happy with the way it sounds. I'm not sure how much of that was from the linear supply, but I don't think it can hurt (except the wallet). 

Regarding driving a 2 ohm load, class D amps have exceptionally low output impedance, and can easily handle a low impedance load. The only limitation is the maximum current. The lower the load impedance, the lower the efficiency the amp will operate, so at some point the amp will protect itself and prevent thermal overload (generally controlled by maximum current). The Purifi module is rated at 25A peaks which is more than enough to hit 800w or more into 2ohms (which is where the amp will voltage clip). It can't sustain this for long due to thermal limitations, but you don't need that unless you have very inefficient speakers. 

So it really depends on how much power is required by your speakers. My speakers are nominally 92db/w efficiency and I have to crank the heck out of them to come anywhere near clipping. I have a peak reading LED power meter on my amps with 32 segments measuring 1db increments. With all 32 segments lit, the amp is close to clipping (50v pk-pk). Most of the time I'm listening, I am barely blipping the second LED (approximately 0.3w). 

I tried the tripath, ICE and Hypex Class D amps.. all the while never giving up my tube gear, using the class D amps as summer amps.
while class D sound clean, clear and dynamic...  the best of them being the bel canto ref600m hypex amps,  I still found them lacking in realism and tonality.. they were missing flesh and blood !  Sounding clean but never involving or inviting.. great bass grip and power.. but too dry sounding, non dimensional.. 
So I’m back into class A amps.. this time SS..  First Watt SIT3 .. 

there are several chinese companies selling HQ LPMs on ebay. A couple years ago I bought one ~ $150 that took my Oppo 105 to a much higher level

Example

Hi-end Linear Power supply Module for update OPPO UDP-205 L3-18 https://www.ebay.com/itm/Hi-end-Linear-Power-supply-Module-for-update-OPPO-UDP-205-L3-18/11288069254...

hth

the best of them being the bel canto ref600m hypex amps, I still found them lacking in realism and tonality..

Yes they use the same Hypex NC500 modules that I have, I found the same they were the best of Class-D’s I’ve heard also, but also found the same as you about the sound, re body and flesh.

I then subbed out the smp power supply’s for a very large linear powersupply, and things improved greatly.
Then for even as much improvement again, I bypassed the input buffers totally and fed my dac into the NC500 module direct, this was a real eye/ear opener, like someone opened the window to the sound stage and depth department, transparent, very dynamic and great bass.
I can now happily listen to them in my second system, which is relatively easy to drive, they still don’t do it for me on the main hard to drive system.

Cheers George