Are you saying the designers of high-end DACs don't know what they're doing?
No, some of them are very competent circuit designers. What you must understand is that there are some very difficult areas of design, such as power delivery, grounding and shielding, wire technology, ESD and EMI. In these areas there are very few experts, even in big industry. I'm talking IBM and Intel. How can you expect designers in small audio companies to know this stuff?
If you were to market a cost-no-object DAC you designed from scratch would it benefit from mods?
Probably if someone identified a higher performing part, it would benefit from replacing that part - a capacitor or op-amp for instance. Also, I am an expert in the esoteric areas that I mentioned above and in the article. I have not spent 30 years designing discrete analog circuits. You dont have to throw a stone far to find one better than me. John Curl certainly can do a better job of designing an amp than me. Even in op-amp design I'm no expert. Industry experts have seen more circuits and solutions than me. For instance, how to do the I/V conversion from the DAC. I only know what I have seen. I'm no expert on this.