How about a dollar figure for what you consider the bottom of the scale of the price performance cure where a preamp will hinder the purity of a source?
it's really not a fixed dollar figure thing, more an awareness thing. it depends on how good the source is, and the level of the preamp you are bypassing, how good or bad the cables you are eliminating. and overall system refinement. you might have an active preamp that is working fine, but upgrade your speakers or improve room acoustics, and now that preamp is revealed to be a detriment. your system situation can evolve and change the equation.
it's like where an integrated dac/pre is better than separates. saving on one chassis boosts the quality of the internal circuits up to a certain quality level.
is that under $3k, under $5k? or maybe under $20k. no hard and fast rule. just don't add a preamp and expect it to be better. it might be different, or worse. it's most relevant when you are trying to judge system dollar allocation and at what point adding a preamp makes sense. take the preamp budget and add it to the source or speaker budget might take you further. better interconnects and power cables for your source might push you further than a preamp (i realize cable performance is not universally valued).
of course switching sources, driving long interconnects, amplification synergy, and remote volume control are all reasons to add an active preamp. but performance can suffer adding those features.
i'm just always cautious about the effect of any preamp. i went 4 years with a passive after i moved on from my Mark Levinson #32 back 20 years ago. i tried 5 or 6 spendy preamps that my passive surpassed or equaled. until i found the darTZeel.
