I see - it was my mis-interpretation of your term 'ladder DAC' that threw me. I hadn't figured it could be applied to both R2R and transversal DACs.
I don't think that this scheme can work with all classD amps, just ones which have the architecture I set out. IRS2092-based amps do, I think some of the Hypex designs use this too. Perhaps it applies to self-clocked classD and not to externally clocked classD. I don't think single-chip solutions such as Tripath and TPA3116, TPA32XX, TDA8932 use the same architecture as they rely on an external clock (not necessarily external to the chip though) and have relatively high impedance inputs.
I control the volume digitally. I shall talk about this on my lingDAC thread in due course, no need to take this thread off at a tangent.
There is another 'naked' one, USB powered with 8 chips $42 Nobsound Mini HiFi Sound Card DAC TDA1387 USB 8X Audio Decoding Headphone Amplifier DTS/AC3 Coaxial Optical Digital Output-in Headphone Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
I actually ordered one before reading here that a proper filter and I/V stage will make difference and (thanks to @abraxalito) there is a project ready. I didn't expect miracles from this DAC, just more musical sound than getting from a modern DAC. Now I will focus on PhiDAC project. This one will be for a smartphone (if not to heavy on power) and I can use CM108 I2S signals from this board, so it will be not completely wasted.
Why not buy an old Parasound D/AC-1000 and upgrade the output stage? You would get 2 Burr Brown PCM63P-J chips, socketed no less plus three linear power supplys, one for the digital stage and two for the analog stages and it's packaged in a very attractive case.
I use a stock unit in my system and love the analog sound.
During an interview with one of the owners of Schitt, he stated that in his opinion the PCM63K was the very best DAC chip ever produced.
These are true R2R chips and the ladder resisters were laser trimmed on the fab line. Expensive when new and long out of production. If you search Dutch Audio Classics you can search what machines had them as new.
BillWojo
I use a stock unit in my system and love the analog sound.
During an interview with one of the owners of Schitt, he stated that in his opinion the PCM63K was the very best DAC chip ever produced.
These are true R2R chips and the ladder resisters were laser trimmed on the fab line. Expensive when new and long out of production. If you search Dutch Audio Classics you can search what machines had them as new.
BillWojo
A quick look at the PCB confirms this is another of Lee's Audio designs but under the 'Nobsound' brand name.
The first one was Topping D30, but it is completely non-musical device. Now for costs saving it has no-name oscilators and is packed with CapXon capacitors. I looked at the excellent measurements, highly recommended, but there was no follow up to the changes in hardware or independent listening tests - my fault, I trusted ASR.
Nobsound device is on the opposite side - obsolete. I realised that Delta-Sigma after 20 years or so may still not satisfy my requirements and on some aspects it is even getting worse, as with improved clarity false detais and butchered harmonics show even more prominently. Nobsound should be a nice device for basic modding, but a serious project will be a PhiDAC, I hope.
In other words - small steps, maybe one day I will even grow to a Total DAC.
Thank you for reminding me about Audio Classic website, if lucky, I will definitely get one!
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