@mitch2 Oh I hear you. I have a '05 Torelli Express w/ Campy Chorus that I can still manage to find NOS replacement parts for but it's getting harder. For brake pads I end up buying 4 sets so I have back ups. My '21 Ritchey Outback has the Campy Ekar and 2 sets of wheels (700c and 650b) and I love riding that on just about everything. A very different feel than the road racing bike so I plan to keep that set up until 13spd and disc brakes are obsolete. I have to approach upgrades carefully with the wife so it doesn't seem like I'm frivolously spending. I just sneak them in and use the "I bought _____ a while back after a part broke" excuse. 

There are, I believe, several factors that lead to listener fatigue. In chasing the ‘absolute sound’ one must address different areas that could be getting in the way of ‘musicality’. One such factor is noise; persistent subliminal noise that could be the result of polluted power for example, or the result of grounding issues. Or you might consider that many of us do not have a properly treated room, which really can confuse what we hear, ultimately causing listener fatigue. While a specific component can be at fault, it may be that a specific component is not the true cause.

Interesting discussion.

I've been through many speakers, some of which I liked a lot but I developed 'fatigue' over time; as much from the tweeter (I think) as with port chuffing.  

Age hasn't helped I think.

I now own 2 pairs of speakers that I really enjoy listening to for long sessions: 1) Triangle Comète 40th anniversary with a 'Magnesium Rose Horn' tweeter: smooth as silk and a lively speaker that throws a wide soundstage.  The second pair are DIY SEAS A26 clones.  Not the last word in detail and extension, but they 'sound' just so right and I know what went into them: the cabs are made of Birch plywood and are nice and solid; the capacitor is a  metalized poly cap from Solen;  the SEAS A26RE4 woofer and the SEAS T35 tweeter that Troel loves.  If anything ever goes wrong with the latter, I'll know exactly how to repair it!  LoL.

Speaker in the past that had that same 'I can listen to it all day' type of sound: An old pair of Mission 710; a pair of smaller Mission Leading Edge speakers.  I'll throw in Harbeth P3ESR and NHT super-ones 2.1; Mirage OM-10. 

The big cause of listener’s fatigue is the un-natural sound. All audio systems in the world sound un-natural (except Wavetouch audio which is an only natural sounding audio system).

When we hear a natural sound, our ears and brain don’t need to work hard to understand. When we hear un-natural sounds, our ears and brain must adjust and work hard to comprehend the un-natural sound. While we hear un-natural sounds, we can’t understand natural sounds such as dog barking or noise from neighbor. So, our ears and brain must quickly change to a natural sound mode. It is hard to our brain and ears switching very fast between the natural and un-natural sound modes.

The un-natural sound makes a listener dizzy and fall asleep easily because the un-natural sound is very confused sounds. It is warning from our brain to our body to take a break. Once broken (distorted) audio signals can’t be restored and most signals are broken from the source (CD Player or DAC).

The characteristics of un-natural sound is confused, grain, harsh, bright, thin, vague, very forward glare, very far sound-stage (tunnel sound), etc. They hurt/irritate our ears always. And our brain and ears are too tired to make out from very confused and vague un-natural sounds. And it causes the listener’s fatigue. Alex/Wavetouch

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