Major mistakes made in assembling your audio rig

Biggest mistake I ever made was going cheap on a digital scale to set up an expensive cartridge. Some cheap $10 weighs anything scale with a flat pan, instead of a $80 one specifically designed for stylus'.
Long story short, I snapped the cantilever setting up a brand new $5000 cartridge. 8 years later, I still have nightmares about that day....

"Major mistakes made in assembling your audio rig"

For those married or with someone - building it in complete
isolation of your spouse for fear of them knowing what u
spent. If something happens to you - it leaves the family in
a quandry.

You can break a few rules imo.
Its ok to sneak some stuff in .... even major stuff - the kind
that a value can be put on easily - i.e. by a dealer.
Just make sure when you sell something - they see it going out
the door.
this is important. you gain points ....
Include curtains in your room - they help with sonics .....and
to hide gear.

Not realizing how important cabling is and missing the beautiful music constrained and hidden because of poor cabling. Turns out the gear was wonderful, but the full potential lost by constraining cabling.

Inconsistent channelization and improper direction of fuses and interconnects. Also, not having the speakers close enough together.

Thanks to all for their forthcoming-ness ( is there such a word???)

Nevertheless, It is consoling to know that other 'philes have made mistakes. I once put the wrong amperage fuse in a new Conrad Johnson PV-8 pre-amp, only to observe one minute later smoke rising from its top vent, and the chassis toasted bagel hot.

The transformer had to be replaced, and worse I was talked into some mods on the pre-amp done for a grand total $650.00 plus local tax. At least, the mods lowered the noise floor as advertised by the tech.

Next, was my "interim retro phrase" while trying to decide on new speakers; so, in the meantime, I bought a used pair of large Advents with the shitty vinyl veneer. Though, to this day, I still believe, the Advents maybe one of most neutral and at times satisfying speakers I ever heard despite its terrible tweeter. I also learned that in the golden years of the original Advents tenure, most buyers were underpowering them. Unless, you wanted to invest in Phase Linear 400 or 700 power amp, and forego the Pioneer, Harmon Kardon, Denon etc receiver

During retro time, I drove the Advents with an Aragon 4004MKII 200RMS power amp, and they sounded very good

In retrospect, high-end audio is a demanding advocation; reading scores of reviews, and hours of careful auditioning components is a given. Too often, we are accused of listening to "equipment" and not the music, being snobs, being elitists, being anti-social. Nevertheless, those of us who prevail, know of the grandeur and the emotional high that a great audio system can produce, and therefore is worth the time and investment.

Maybe at our most petty and obsessed, we are just sound junkies, but the apprehension of well recorded music, and the personal satisfaction it brings, is not accessible by just walking through a room while music is playing, and humming.