This question has to do with the hair-shirt minimalist philosophy vs. the "complication isn't necessarily bad" one. I see preamps (let's take an Audio Research as an example) that do one and only one thing - amplify & switch input signals before passing them on to the power amp. At the far end of the spectrum, I see AV preamps that have equalization, digital processing, room analysis, and the kitchen sink.
The prevailing audiophile dogma seems to be that the complicated preamps sound not so good as the simple ones. Yet I see startling examples where this isn't so - to wit, the recent Absolute Sound kudos to McIntosh for a variety of their (less than simple) solid state and tube preamps. The McIntoshes include tone controls, significant switching, and far more parts than the Audio Research of the same price range, yet both receive rave reviews.
Of course, I understand that the quality of parts and engineering can overcome some of the design choices (compromises?) that must be made to integrate more functions into the preamp. Nevertheless, is there a point at which no amount of parts and engineering quality can overcome the disadvantages of the design's complexity? If so, where does that point reside? Do the addition of:
Balanced and unbalanced inputs & outputs
Surround sound decoding
Room analysis & correction
damage the sound beyond redemption compared to the Audio Research that lacks these features? Which features do the most damage and which are most amenable to parts quality and engineering remedies? If features are irrelevant and circuitry design is all that matters, why don't the minimalist companies add features wholesale?
Before I invest a significant amount into a preamp that I may have to purchase without a meaningful audition, I'd like to clearly understand what features to look for and what to avoid. I realize that this may be a hopeless quest due to the number of variables, but I'd feel negligent if I didn't at least make an attempt to understand.