Thank you for replying! It would be very nice if you could perform an objective test. Unfortunately, I don't plan to visit the States the next months, but you are welcome in Europe (Belgium)
you could mail the completed boards and I would test them similarly to how I did boinger's boards. I have an automated data collector that can step thru every single db value and measure the real db attenuated. I later plan to do freq response checks (adding another inner loop). this might be the most telling of the tests.
so, if you are game to spend the money on high end resistors, I'll offer to run some number gathering on them.
my guess, though, is that it won't justify its cost in terms of numbers. but I really dont' know as I've not built with expensive parts yet. the 30 cents per vishay is about as rich as I have ever used, on this project
I agree that all resistors are in the signal path, including the parallel ones. But the way I understand the schedule it is the following: when the relay bridges Rp, than Rp is outside the signal path; when the relay connects Rp, part of the signal is diverted to ground, and will not appear at the output. If this is correct, then the quality of the Rp resistors will not influence the signal quality, is that right?
when a relay is in a position to short out the series R and 'let go' of the parallel R, neither of those are 'in the circuit'
BUT, in the other case where the relay is not like the above, then both are in the circuit. how could one be and not the other?
if you really want to get high end tweaky (lol) then you can skip all the 'bad steps' that have the most amount of stages in play. each relay is a bit and that is a stage. the stage is either fully bypassed and out of the equation or its in-play. numbers like 7 that have 4+2+1 (the bottom 3 stages all in non-bypass) are 'more evil' - if you want to see it like that - since they take more stages to do their work. the saintly number 8 takes only 1 stage to be in play and all the rest are at rest
you start to get more and more evil as you get to 15, then you are saintly again at 16.
and you SEE this if you run passive. with no buffer, the more evil you get, the more noise you really do hear.
and so, you should only allow yourself to step to 0, 2, 4, 8, 16, 32, 64 db and that's it.
but if you have a buffer directly (very very directly, measured in millimeters) after then the evilness is nullified to a great extent
this is why I insist on running with an active buffer after my d1 attens. only exception is when the d1 is co-located inside an amp and that amp is the buffer.
I guess what I'm saying is that the R's on the d1 board are not going to change your sound, at least I don't think they will. but spending your time on getting the best electrical (logical, short wiring) connection between the d1 and its buffer; and also the psu for the buffer, THAT will be your payback for money spent.