Is DEQX a game changer?

Yes, an excellent post by Bombaywalla, and an excellent response by Michael (Swampwalker). Thanks, gentlemen!

I am in full agreement with both posts, aside from what I believe is an inadvertent and minor misstatement in Bombaywalla's post:

A linear power supply is expensive from a power dissipation perspective - you have to design its max voltage for the max peak voltage of the program material but in normal operation the linear power supply operates mostly at the average voltage of the program material. The difference in the peak & average voltage is dissipated as heat. Of course, you don't know what the max voltage of the program material is so you have to over-design further leading to more heat dissipation.

Shouldn't it be the output of the amplifier that has to operate mostly at the average voltage of the program material, not the output of the power supply? With the difference between the average output voltage and the voltage supplied to that stage (which as you indicated has to provide headroom relative to the maximum anticipated output voltage), multiplied by current, corresponding to the heat dissipated in the output stage, not the power supply? Although the heat dissipated in the power supply will also vary with current demand. And although there are a few amplifier designs in which the output voltage of the power supply is actually varied among a number of discrete levels as a function of signal level, some of Bob Carver's older designs being examples.

Again, though, an excellent and informative post. Thanks!

Best regards,
-- Al

Hi Almarg,
yes, you are correct - misstatement on my part. Sorry guys!

indeed the linear power supply operates at its designed output voltage (which is over-designed to ensure it will accommodate the max program material voltage) & the extra power dissipated will be (power supply voltage to amp output stage - voltage of program material) * current. And, correct again, the power amp output stage mostly operates at the average voltage of the program material.

I have just read these posts about the DEQX power supply and yes, I too had noticed the apparent 'downgrading' from the supposedly superior linear power supply in the HDP4 & HDP3 models

In support of Nyal, he also gave me some excellent advice when I was setting up my DEQX back in 2012 even though I am back in his 'mother' country and not a USA customer. He seems a true professional to me

I have a suspicion that the reason for his evasiveness is that he doesn't actually know and would rather not give a definitive response without knowing the facts. Whilst I absolutely endorse the products, most times I have emailed the manufacturer themselves a direct question I have received a (late), oblique or non-answer so maybe Nyal has the same experience? Their one major weakness appears to be 'retail' customer interaction, it may be different for the pro or OEM market

I also guess that listening differences in power supply would probably be very small in real world listening rather than worrying about specs alone. I have heard a system with the original PDC 2.6, an older Premate, the HDP3 and a different system with an HDP4 and all share the same remarkable transparency, clarity, imaging and realism

I also know from another European manufacturer that legislative bodies seem have an ever tightening influence on the types of PSUs being acceptable so possibly DEQX are reacting to this in the HDP5

Bombaywalla, you and your comments are certainly respected.
I lack tech knowledge and so must re-read these last posts. However Drewan I believe a "most refined" power supply is the basic requirement of a great product.My experience has taught that as your basic equipment, pre & amp, become of exceptional quality it is noise that limits the ultimate refinement of the music and to my ear it's very noticeable; not as noise per se, but as limiting dynamics,nuance and particularly the spatial presentation of the orchestra.I know how even minute amounts of noise have a significant effect in my Spectral & MIT system,as I have experimented & invested in quality power conditioning & isolating products which allow the ability to "cascade" complementary products in a very revealing & informative way.My Spectral DMC20 pre has a 'highly touted' separate power supply (which I came to feel was the units weakest link as I thought that a robust power supply should 'perfectly' isolate the effects of ac noise). My system reveals how insidious any electrical(perhaps also magnetically generated) noise interferes with the systems ability to render the magic of great sound reproduction. The DEQX is "an added link in the chain" which can only add noise!(then consider cabling). I can't help it - the more this is discussed the more I feel the move to the switching power supply is "only" about saving money. Transportation costs are becoming a more significant aspect of cost all the time.

Drewan & Ptss, thanks for your latest comments, which are valued as always.

Pete, a point to keep in mind is that a downside, or at least a potential downside, of the extraordinarily wide bandwidth of your Spectral equipment can be expected to be increased sensitivity to any RFI/high frequency interference that may find its way into the circuitry of those components, compared to components having more typical bandwidths.

Also, as I pointed out earlier the PreMate, which was well reviewed by Kal and has been found to be beneficial in Bruce's (Bifwynne's) very high quality system, uses a switching power supply.

Finally, it would seem understandable that the internal real estate and the additional power required to support inclusion in the HDP-5 of the touchscreen and its associated CPU and other circuitry could very well have necessitated going to a switching power supply.

Best regards,
-- Al