As to the Benchmark L4 versus the CJ pre-amp, one of the comments was The LA4 certainly isn't "lacking" anything. It's just transparent. But I could say it does 'lack' certain things in the sense of comparison to the CJ tube preamp. Based on my experience with both brands, I found CJ to have a house sound, not one that I or my friends prefer. The Benchmark, on the other hand, stock is clean and clear but lacking in areas the CJ excels-body and warmth of expression.
There is a cure for the Benchmark. Replace the computer quality, cheap-ass regulators, power and filter caps, maybe parts of the audio board, the Op-amp, etc. with audio (much more costly) parts. Benchmark products are only okay stock but can be great when modified. Their HDR-1 DAC is a great example of a terrific design with mediocre execution. It is a giant killer when modified.