Charlie was a character, but unfortunately, the posts you link while having some wisdom, are also lacking. The article linked to written by Barrie Gilbert at ADI does discuss slew rate limiting and other potential issues related to I-V implementations and virtual grounds using analog op-amps. However, that issue is typically more a concern with high speed, high bandwidth DACs, of which audio DACs rarely are these days with much of the analog inside. Of course, the simple fact that many op-amps for audio are specified in this condition, not to mention that a simple distortion measurement on the completed product will reveal if this is an issue in the completed design. When one links to an article, it is probably best if one understands it. I am not sure Charlie did. Discrete components are not a panacea either. Integrated devices allow semiconductor component matching not possible in discrete devices, much lower parasitic values, and often enable circuit complexity (in a good way) that discrete devices do not allow. In Charlie's rant on China, and LKS, he just comes across to someone experienced as "angry". Absolutely there can be issues in assembly in China, but his "analysis" of LKS based on a flawed photo review does nothing for credibility. The pins on the DAC are not bent. Simply zooming in would show that the PCB pads have staggered solder mask foot print lengths which zoomed out makes the pins look bent. The black solder mask is obviously for looks. Picking on "Chinese" PCB mount heat sinks? That removes any sense of credibility from his writing.
Oh DAC versus speakers? Bluesound 2i is good, but just that. There are better cheaper units. Something just is wrong with the sound of it. Sounds like you have good speakers so an upgrade is likely worth it there, but realistically, for most audiophiles, and I would include the vast majority at almost any spend on their system, the speakers in combination with the room are the limiting factor. It is one of the primary reasons why audiophiles are always swapping out components. If you don't fix the basics, then you are never going to be happy with the sound. It will never sound right. The best analogy I can give is the difference between a professional photographer with a point and shoot camera, and a rank amateur with a top of the line DSLR. Sure, you zoom in, and those images on the DSLR will have lots of resolution, but the composition is awful, the lighting is poor, and the subject matter uninteresting. The images from the point and shoot won't have the resolution, and will have higher noise, but will be far more visually pleasing because the most important things w.r.t. what pleases people in an image will be far better. Everything does not matter equally in audio reproduction. I would rather listen to 320kbps MP3 on a really well acoustically implemented system versus 24/192 on an expensive but acoustically poor system. Sure I will recognize the limitation of the MP3 files, but overall it will be much better.