Is "detailed" audiophile code for too much treble?

Bottom line is higher frequencies are an essential part of detail. They can also be a key source of noise and distortion which lead to fatigue.   It all is needed and all needs to be done well ie have a handle on noise and distortion.  After that it’s largely a matter of tuning to personal preference. 

It only means what people think the word describes. There are some who seem to equate lots of detail and transparency with a bright sound. But many don’t. There’s no definitive answer.

Some people say a highly detailed system is a little bright. Think of the opposite, a warm or lush sound. Wouldn’t that at least imply a loss of detail? So it’s just words that people assign to their own understanding of sounds. Some words have almost universal agreement, some don’t.

If you think about it, a flat frequency response SHOULD provide the most detail because if you have a dip in the response you loose detail through that area, and if you have a peak, you mask detail in other areas.

If you have a flat response to "beyond hearing" it will sound bright because most people are used to hearing "rolled off" highs.

^^^ But since human hearing is not flat, a flat response could yield all kinds of lows and highs a particular listener does not want.

To answer OP’s question, I think of detail as the ability to hear distinct sounds in the program material. Like when I upgraded my audio interface to film capacitors in the analog stages, and suddenly I could hear sounds I didn’t know existed. I could hear the timbre of a wood-bodied instrument, such as a cello. I could hear the ugly sound of guitar strings rattling against one of the forward frets, even though I was pleased to actually be able to hear such a detail. It is in fact a caveat to have a detailed (read that: revealing) system because it shows you when a recording is truly bad.

I don't see why a bright system is associated with detail.  It's a different phenomenon in my opinion.  I think Sennheiser HD's of various models are bright sounding, but this doesn't give them any increased ability to be detailed.  I'd say the equipment behind is has greater affect on detail.

Some of it probably comes down to semantics and ascribing different meanings to chosen terms, but to me "detailed" in sound reproduction often reads as something that draws attention to itself apart from or outside of a holistic aspect of the presentation.

By comparison how would one describe the sound heard from live acoustic instruments playing? Mostly I don’t think of "detailed" when listening to a live symphony orchestra, but rather ’liquid, flowing, natural warmth, uninhibited in scale and dynamic swings, lack of smear, less pinpoint and more amorphous, a swell of sonic force coming in waves’ - something along those lines. With smaller ensemble, more intimate live acoustic concerts the physical aspect and precision of placement often becomes more prevalent. Sitting close to a grand piano is quite an experience and quickly lets you know how most speakers would simply collapse trying to replicate to sheer wallop, power, presence and size of presentation such an instrument is capable of. Not to mention tonal aspects all the way down into the lows with the frequency range it requires - it’s a beast.

Choosing components (incl. cables) and speakers, setting filter values (actively), tweaking acoustics and the placement of speakers to me very much comes down to approximating that desired "informative within the whole of presentation," where the sound is more or less framed by a cohesive sphere of sound with a solid core to it. I don’t want to hear treble as I do overtones ingrained with a primal, timbral imprinting; HF that doesn’t draw attention to itself but has substance linked to the instrument or voice from where it originates. Same with the low frequencies for that matter - I just want them to uninhibitedly "be" when required and part of the presentation as a whole. Sound like that mayn’t impress at first (or, to some even later on), but to me it’s certainly the more mature and natural presentation.

Of course there’s also accounting for the Munson effect and the variations in perceived frequency response at different SPL’s. I could operate with a different filter preset for very high or low SPL’s (but don’t), and thus using a usually fixed reference SPL for setting filter values does imply that listening at either quite low and very high SPL’s doesn’t present the best overall balance of presentation. I’m not really bothered by that being I typically listen at or around ref. volume level.