← Charles Tay Learning in public ·

How I decide with AI

A year of hi-fi decisions, and what AI spotted when I asked it to look back.

how to read this

Hi-fi was new to me in late 2025. It was personal, so I can share every step, and it cost real money, so I had to think each step through.

Each decision shows what I asked AI, what I did myself and what I decided. AI came in where I needed something explained or checked. Some steps didn’t need it.

In October 2026 I gave an AI assistant a year of my past chats and asked it to rebuild my decisions. My prompt, roughly: “Rebuild the search pattern and decision points of my hi-fi journey, starting from the setup I used before the SP3000T.”

What it found is in the looking back lines. Some choices held up. Others only looked sound one at a time.

decision by decision

My questions to AI are quoted as I typed them, typos and all. Months are approximate.

  • late 2025
    start from the need

    Better sound for editing video

    did myself
    Bought closed studio headphones. On my first shop visit, added a small USB-C DAC/amp so my iPhone could play lossless music properly.
    decided
    A practical fix for work. Not a hobby yet.
    looking back
    My memory was wrong. In an April chat I said I got into hi-fi in 2023 or late 2024. The chat records put this step in October to November 2025, so the whole run took about six months, not two years.
  • Nov 2025
    which player?

    Which portable player?

    asked AI
    To explain in plain English how the players I was considering differed in sound.
    did myself
    Took my own phone, DAC and headphones to the shop as a fixed reference, so only the player changed. Listened to several players in one afternoon.
    decided
    The SP3000T with its tube stage on, over the SP4000, which is the better player on paper. My ears decided.
    looking back
    The fixed reference and the side-by-side listening held up. But most of my information came from one shop I trust, so its stock shaped my shortlist.
  • Nov 2025
    one setup or several?

    One setup for everything?

    did myself
    Listened to open-back headphones at the shop and compared them with my closed pair.
    decided
    One setup per place: closed headphones outdoors, open-backs at my desk, in-ear monitors on the go. Later, speakers at home for listening with family.
    looking back
    Held up.
  • Nov 2025
    which earphones?

    Which in-ear monitors?

    asked AI
    “64 audio IEM u18s is what type of IEM and drivers”. Plain English before spending.
    did myself
    Left one shop visit without buying because the choices were too complex. Came back, listened again, and tried another brand that I found so-so.
    decided
    64 Audio U18s. I noted a custom-fit pair as the upper limit, not the next step.
    looking back
    I paid in instalments, and judged it by the monthly amount, not the total.
  • Nov 2025 to Jan 2026
    will it fit?

    Upgrade, or use what I have?

    asked AI
    “Does toxic cable medusa2 drive u18s 64 audio Iem”, and later “u18s 64 audio what modules provided”.
    did myself
    Narrowed a shortlist of six cables to one after checking the pairing. Swapped a bass module on the U18s before shopping for anything new.
    decided
    The Medusa 2 cable. After that: change what I own before buying more.
    looking back
    Each purchase raised the next question: player, then earphones, then cable.
  • Feb 2026
    check the claim

    Is the salesperson right?

    asked AI
    “I was told my sales person that FitEar IEM are very desirable by all audiophiles?”
    did myself
    Treated the line as a claim to test, not a fact.
    decided
    Didn’t buy.
  • Feb 2026
    set a limit

    Am I done?

    did myself
    Decided I had reached the end of portable hi-fi. Kept a short watchlist instead of buying.
    decided
    Watch, don’t buy.
  • Jun 2026
    then break it

    The limit didn’t hold

    asked AI
    “Research and compile a ‘Real-World Ownership Report’ for the Astell&Kern SP4000…”. By now I set the brief: owner reports on heat, battery life, build and software, against the player I already had.
    did myself
    Lived with the SP3000T for six months first.
    decided
    Bought the SP4000, a few months after I said I was done.
    looking back
    The research was thorough. The limit I set in February didn’t survive it.
  • Oct 2026
    what changes

    What I do differently now

    Two rules from now on. I look at the full price, not the monthly instalment. And before I buy anything, I ask what it will make me want next.

how I learn anything new

Hi-fi was the subject this time. I follow the same steps with new AI tools and new topics at work.

  • plain English first

    Ask for the simple version and don’t be embarrassed by it. I still do.

  • check, don’t trust

    Reviews, owner forums, known faults and sales pitches all get the same question: who says so, and do other owners agree?

  • try it in person

    Listen in a shop. Same song, change one thing at a time. My ears decide, not the forums.

  • live with it

    Six months with one player taught me more than any review. The second player made sense only after that.

  • ask AI to check me

    After a run of decisions, I ask AI to go back over my reasoning, not only to explain things beforehand. It remembers what I said better than I do.

  • know when to stop

    Most of what I looked at ended in “I don’t need this.” Not all of it, as the last two decisions show.

Another case: choosing a laptop for AI, where my own test overruled AI’s advice.

the details

All my questions, in order
  • Nov 2025
    what is this?

    “is this a gold cable ? How to tell layman in one sentence”

    Also: “64 audio IEM u18s is what type of IEM and drivers”. I started by asking for plain English, one word at a time.

  • Nov 2025
    will it work?

    “Does toxic cable medusa2 drive u18s 64 audio Iem”

    Before buying a cable, I checked it suited the earphones I already had. Then I asked how it would change the sound.

  • Dec 2025
    how do the parts fit?

    “If i use M21 to WA7 3rd Gen vs SP3000T to WA7 3rd Gen vs SP4000 to WA7 3rd Gen. Sound signature ? In Layman”

    Still asking for plain English, but now about a whole chain. The answer changed how I saw it: over USB, the player only sends data, and the amp at the end decides the sound.

  • Jan 2026
    use what I have

    “u18s 64 audio what modules provided”

    Before shopping for something new, I learned to change what I owned. Swapping one small module trims the bass.

  • Feb 2026
    check the claim

    “I was told my sales person that FitEar IEM are very desirable by all audiophiles?”

    A salesperson’s line, checked before I acted on it. I didn’t buy.

  • Jun 2026
    set the research

    “Research and compile a ‘Real-World Ownership Report’ for the Astell&Kern SP4000…”

    Eight months in, I no longer asked what things were. I set the brief: owner reports on heat, battery life, build and software, compared with the player I already had.

What I ended up with, and the year in numbers
looked into
23 players, amps, earphones and cables I didn’t buy
bought
6 items, each after auditioning or checking the pairing
waited
6 months before adding a second flagship player
  • Nov 2025

    Astell&Kern SP3000T

    My main player. It has a real vacuum-tube stage you can switch on or off. I compared it with the SP4000, PD10 and iBasso DX340 first.

  • late 2025

    64 Audio U18s

    In-ear monitors with swappable modules that change the bass and how sealed they feel.

  • Nov 2025

    Toxic Cables Medusa 2

    Chosen from a shortlist of six cables, after I checked it suited the U18s.

  • Dec 2025

    FiiO M21 and MUSE HiFi M6 Double

    A lighter player for days I don’t carry the SP3000T, auditioned at AV One, plus a portable tube amp I tried at Jaben on a friend’s advice.

  • Jun 2026

    Astell&Kern SP4000

    Added after six months with the SP3000T. One is for relaxed listening, the other for hearing every layer.

One thing I didn’t expect: I felt a faint tingle in my ear while the player was charging from the wall. It never happened on battery or a power bank. If you feel it, unplug and get the charger checked.