Serious Passive Preamp question

For a passive, I don't think that would be worth anywhere near $2200.  It's just a couple of stepped attenuators using larger "through hole" resistors.  It doesn't even have anything special, such as signal transformers like other exotic passive preamps.  Definitely not worth a trade for a LS7 linestage - you're, essentially, getting screwed on this trade if you do it.
If you really want to see what a passive does, try a Gold Point SA4 ($532), or an SA2X-I if you want balanced XLR passive ($616).   If you really want to go on the cheap, Shiit SYS for $49.

As I have said before, a passive preamp can be a tool, but it really depends on your source/DAC and your amplifier.  If you have a DAC that is very fast and solid-state sounding, I think a passive is not really the right tool as you need an active preamp in the middle to help smooth and shape those hard-edged waveforms.   If you have a full Class A or tube DAC/source, then a passive could work well.