Hi Daniel,
This has come up a lot here so I've opined about it before, but since you ask...
I work in pro (TV/Film) sound too and have spent lots of time in mixing theaters that have been designed to produce very accurate sound. It's great. I can also enjoy both "accurate" sound systems (e.g. neutral frequency response,low coloration) but like your engineer pal I also can and do enjoy systems that do have some level of coloration. For my home listening.
So for instance, while I tend to choose generally well designed and pretty accurate loudspeakers, I use tube amps because I feel they add a little something I enjoy.
From my observations of audiophiles over time, to make a point, I'd make two overly broad generalisations: On one hand there are those who seek to make their systems simply "accurate" reproducers of the recorded signal, and then "however it sounds...that's how it sounds."
Others want the sound of their system to "sound more real" or mimic what they find to be characteristics of real instruments and voices.
(There is overlap of course, but I'm deliberately using broad strokes).
I find it is more usually the latter cohort that tends...perhaps surprisingly on first glance...to extol things like tube amps, or horn speakers or generally be more accepting of colorations, and talk about how the sound relates to "how things sound in real life" vs "I can pinpoint deviations from technical accuracy." It doesn't of course mean they are RIGHT in their claims, but in terms of motivation, it seems to me to be a trend.
So to take myself for an example. Please understand I'm not arguing that I am "right" in the following, but simply describing my own psychological motivations, which you seem to be asking for:
I've always been obsessed with live vs reproduced sound. I've done live vs reproduced comparisons with instruments and voices through various sound systems, I'm constantly comparing the characteristics of live sound vs reproduced, because it fascinates me and also because I find the sound of real instruments and voices to be sensuous and luxurious in tonal warmth and complexity.
And I have noted that it is ONLY when a sound system either transmits, or at least mimics these aspects to some degree, that I'm at all compelled to sit down and listen. Otherwise, I'm just happy listening to music on any device as I do other things.
First: it's a whole other discussion as to what one is actually hearing, listener bias etc. But I think it's fair in the context of the topic you raise "why prefer coloration?" to, at least for sake of argument say "
Ok if we GRANT the colorations one hears are in fact being added to the system...WHY would you want to add them?"
So in that spirit, I'll get to my subjective impressions and motives:
To get right to adding coloration: in a nutshell I found that certain tube amplification seemed to add something to the sound of my system that reminded me more of what I hear in real life sounds. A bit more rich, round, soft, relaxed, spacious, filled out, 3d, and a sort of texture I like.
All of it is subtle, but adds up to a significant, to me, subjective preference.
So for instance I find my old CJ Premier 12 tube amps do that, but also seem to add this slight "golden upper midrange glow," like a slight illumination to the sound, which to me not only sounds pleasant: it mimicks real sounds a bit more. By that I mean, in comparison solid state amplification in the system sounds a bit more "canned," electronic, recorded, like the instruments are encased in the amber of the recorded ambience, separate from my room. That little bit of air/upper midrange illumination and texture seems to sort of "uncan" the sound for me, more like the instrument or voice is happening "in the same acoustic/air" as the room, more like seeing right through the speakers to being in the presence of a "real" voice or instrument.
Again, this is subtle stuff not "hit one over the head" differences. But subtle changes can have big subjective effects depending on what someone tends to notice or care about. It takes only a teeny tweak of an eq, objectively speaking, to make sibilance in a voice recording too hot, but even that teeny tweak can be the difference between the voice sounding natural and being cued to it being artificial.
So for instance I have been constantly amazed by one pair of speakers I own, little Spendor s3/5s, at how they capture some essential qualities of the human voice - the softness, roundness, fleshiness. When I listen to a naturally recorded female vocal and compare to my wife's voice, it sounds more organically like the real voice than most reproductions (to me). A while back I put a Bryston amp in to the system and when playing those tracks they immediately sounded to my ears less real - voices now had a slightly hardened, squeezed, tight sound that signalled "this is reproduced, a recording." It made me realize it wasn't just the speakers only that had been producing voices so convincingly, but the combination with the tube amp.
So...that bit of coloration from the tube amps, I find, just seem to make my speakers "disappear" from my mind as the source of the sound, and overall the "system disappears more" in it's mechanical nature, and I just more easily slip in to the sonic illusions on the recordings.
I don't think everyone else would make the same choice, but that's how I hear things.
But...what about "High Fidelity" and "accuracy?" Am I just abandoning those?
First, while many here use the term "
High Fidelity" to mean "
technical accuracy" keep in mind that actually wasn't the original use of that term.
Or at least not strictly. Originally "
High Fidelity" sound was often touted as being about "
High Fidelity To The Sound Of Real Voices And Instruments." In other words, that a sound system can produce a sense of realism. That's why so much of the original ad literature for "High Fidelity" sound equipment bragged about just that aspect of the sound. This was typical at the dawn of High Fidelity claims:
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But it's perfectly fine to update or adopt a definition strictly related to technical accuracy, so long as the definition is stated and everyone is on the same page with that. (Though I think the above should be kept in mind whenever one encounters the claim "High Fidelity means X and therefore you aren't interested in High Fidelity if you are deviating from that").
Anyway...I don't fret over a loss of accuracy not because I don't care about it - I want recordings to exhibit their particular characteristics. Rather it's because I find the colorations I am introducing, while subjectively significant, are so tiny with respect to the characteristics on recordings, that the recording character completely swamps whatever colorations I'm introducing. Every recording sounds utterly different, all the musical and production choices in evidence. Fine detail and insight in to the recordings is incredible, VASTLY beyond the average consumer's sound system. I even have musician friends bring over their different masters of their music to check out, because all the minute choices they made are easily distinguishable.
So, no, I'm not sitting around fretting if my system isn't accurate enough, as if I'm missing some important musical message or information.
I've introduced just enough character to produce a significant subjective impression on sounding a bit more "natural" to my ears, but not enough
to wipe out all the relevant differences in recordings.
I hope this explanation makes some sense to you.
Cheers.