Digital input amp

I see a few coming on market.  Previous threads were quite old.

They take a USB or other input. No DAC on the front end. Just the DSP engine to do volume, eq, etc, then whatever conversion to PCM to feed the class D output. So the only "DAC" is the output stage.   This makes sense as it further reduces the functions in the chain.  I have not seen objective testing or any reliable subjective testing. The ones I have seen are Infineon processer based. No idea if the output filtering or feedback implementation is up to the Purify quality.   I guess the next innovation is the GaNFET output.  One has a DAC to feed a sub out. Easy as any old $5 DAC will wo there. 

I was browsing and came across the Sajab A30a. ( quite inexpensive)  Peachtree has the old Gan-1 but coax PCM only.  That would be fine if it managed buffering and clocks internally. Unfortunately my all-in-one only has USB out. 

I suspect there is a lot to be learned here but it makes sense to me for the future. 


Very interested in the mods. I visited a showroom ( dealer for both Peachtree and Bluesound) and their conclusion was neither were quite high end yet and are not carrying those specific products.  They did suggest some of the esoteric amps using the GaNFets were very good. But for mainstream non-exoteric those of us who have to spend real money, the better of the A/B are still winners.  They suggested there are much better streamers than the Blue Node.  That leaves me with a lot to research.  Bits may be bits, but what you do with them matters.  Things seem to move fast though.   I'll look up the D-H stuff. 

This technology makes sense to me from the engineering side. Probably really bad for DAC and preamp makers. If the market is there, we need someone to do an ASIC for the entire front end and then high end will be affordable to the masses.  Low volume, I guess FPLAs.  Hear that, Masimo?  You have the wherewithal to pull it off!  The smartest engineering  Mom and Pops are not going to get the volume needed even if they come up with the breakthrough ideas. Even Bruno has not got there yet. 

From the PA-10 WEB, I could not tell what technology they were using. Some sort of hybrid maybe.  

 I see one here just can't stop insulting people. Sigh.  Nobody can learn anything that way. 





I see one here just can't stop insulting people. Sigh.  Nobody can learn anything that way. 

Actually @tvrgeek, here's a heads up.  Most of us here have a fairly thick skin.  But what would you think about someone who starts a thread and then tells a great designer of amplifiers he does not really understand how an amplifier works?  And then when it is pointed out feels he is insulted?




 @jetter +10,000 Ralph has forgotten more than most will ever know. He is  respected and is a proven source for knowledge, world class amplification and engineering/design. Gads unlike a certain someone. Sigh and he/she has nothing to offer from stand point of teaching and thinks he is the smartest guy in the room, sigh.  

@tvrgeek Lets impart some knowledge on the PA-10.

I’d guessed given the overall sound of the PA-10 that it was in some way Class D in its architecture, but Gold Note makes no mention of this in their technical specifications. Personally, I’m a massive advocate of Class D technology when it is done well and so I asked Gold Note directly “What Class of amplifier is the PA-10?”. Here is the response I got – “ The PA-10 features quite an interesting design. It is not a Class D amplifier but it leverages a new technology that uses MOSFETs for the output stage, in common with the Class D, featuring an output oscillator (GaN Mosfets with Gallium Nitride), a proprietary design that actually doubles the power of the amplifier when reducing the impedance – exactly as a pure Class A but with extremely high efficiency to deliver great amounts of energy.” So there you have it. 

Sad Gold Note only gave marketing BS as a description.  I would love to see an IEEE or AES paper on whatever they are doing to see if it really is innovative. The  bummer is it is within my price, but only direct sales and no audition/return policy I could find. Their published specs are not defined so even though they are not impressive, not knowing the parameters makes them meaningless.  At what power/frequency is .01% distortion?  Is it .0001% half a Watt lower?   Could be a great amp, could be not so.  Totally useless specs. 

"Well executed" does seem to be the issue. I guess my best bet is a Buckeye/Purify based amp. Either that or go the safe rout with a Schiit Vidar.  I have recently heard a Hypex based amp and it is far better than the older ICE amps or the new CH-FI $80 wonders, but not there yet. 

The mentioned Peachtree "digital input amplifier " I started the thread on, maybe some clarification.  Their point is they did not have a DAC on the front end.   Their block diagram, not mine. 

If the specific implementation of using a triangle and an analog signal to generate the PWM control only being class D, then that implementation needs a DAC somewhere along the line before the conversion.  Two DACs if you count the output filter.  That is not what they were saying as they  do the entire processing from PCM to the PWM control in the digital domain.  I would still call it a class D, just a different way to get there. That is what their literature says.