Skibum- glad to hear you had success with your very first Mod outing. Feels empowering doesn't it! Now you are free to tackle the rest of your system, one component at a time, imagine the possibilities! Keep it simple ...Keep it real.
Myself I modded everything "but" a DAC up until last August when my first Valab DAC came along. I knew virtually nothing about the inner working of a DAC, the whole thing was black art to me. However once I delved into the Valab I soon discovered most of the black art is actually inside the digital to analog chip itself and DAC designers can do virtually nothing about it. They are digital interface and analog output engineers, my goal as always is to paint them out of the picture. Modern DAC chips just give them lots of choices on how to implement the in's and out's. Think of these choices like the many inputs to the Chameleon DAC, IMO its best to focus on perfecting only the one. Multiple inputs only offer the chance for multiple issues.
As everyone knows the Phillips TDA1543 is a legacy chip from 1990. The beauty is in its large size, simplicity, and I2S input with no fancy options ... none. Perfect for the DIY guy to mess around with. As the chips became surplus in the mid 90's a man named Ryohei Kusunoki with some clever inspiration discovered how to implement post DAC filtering using only our ears. The NOS DAC was born.
TNT-Audio inter.views Kusunoki San [English]
Just like the SET amp, using current measurement technology, the NOS DAC shouldn't sound superior ... yet as we all have discovered ... they do. As the old adage goes."If it measures bad and sounds great ... you are measuring the wrong thing" I think of it like the current crop of 3D movies coming out, I have no idea how it works but boy is it more realistic. Ironic then that making the Chameleon an I2S input only DAC actually adds a complexity. I have found this theme to be present in all ultra simple audio applications, the last hurdles are always the highest. What's cool about the the M2Tech HiFace is it removes the high hurdles when using computer audio at a very attractive price. I myself would prefer if JKenny would offer a galvanic isolated HiFace with 5V I2S output and battery power supply. That way you could eliminate the entire main circuit board and its limitations. (By the way I have yet to hear a pop with the I2S direct connection.) What remains is figuring out how best to direct terminate the I2S wiring, its obviously that the current factory set up is also far from ideal. I still find it valid for the brazen modder to try I2S direct to the DAC board ... be it transport or HiFace. Who's with me?
Having said that I hooked up my fully modded Chameleon DAC with Spdif input and my partially modded Chameleon I2S and put them head to head. This was easy as the Pace Car can simultaneously output both I2S and Spdif. It was just a matter of selecting the source select on my Silverstone Ultimate TVC. While the differences were not large there where meaningful observations. First it's clear I need to finish installing the Blackgates & film bypass caps on all 16 DAC chips of the I2S version. It lacks global dynamics. However the Spdif version lacks what I call Valoomph, a word I have coined to describe hanging musical nuances with dynamic slam. To get crude it’s like taking a massive dump that comes out all at once with no need to wipe afterwards. Every note hangs in the air for just a millisecond longer and decays naturally into the ether. Subtle yet deluxe.
Could I live with the Spdif version as modded, yes you bet. Could the Spdif input sound better with simplification and better external clocks, yes I already proved that. Would there be lower jitter with a better clock on the upsampling board, yes Rhodes & Tony have already pioneered that trail. Will these mods reveal Valoomp in my system, you bet. Understand however there are levels of Valoomph ... will you still need to wipe after you mod. Depends!!!
The question is ... Choices.