What has been your costliest mistake in this hobby?

I always shut down to change a rig. Biggest mistake was putting an opamp into EE DAC wrong orientation.  Not a major dollar crisis. I triple check all connections,  so no kabooms.

Dealt with two liars over the years, an that cost me a few hundred. 

The only big very big mistake i made in buying something, was after reading universal appraisal reviews of a very well known amplifier....I will not name the designer company... They dont deserve my wrath, aome reviewer does perhaps, but even them only win their life and bread then.... I am the only culprit to beat....

The amplifier was so bad that me and my friend were flabbergasted and laughing after one minute listening.... It was a perfectly working unit, i sold it immediately and easily few hours later....

Any piece of trash will be the heaven of some crowd.... :)

I was at this times looking frantically for "upgrade" for my unsatisfied audio system...I have not understood how to improve any audio system at this time.... But sometimes we must change the amplifier we have because it is a limitation.... I am not against upgrading , i am against ignorance disguised in "upgrading costume"...

:)

Sorry i will never reveal the name of this universally loved piece of amplifier....

Foolishly bought a pair of speakers and:

1.  Didn't negotiate hard enough and paid $2K more than I should have
2.  Listened to the dealer when they said it would work in my room

I naively assumed that a dealer would actively try and solve my problem rather than just sell me anything they could.  The dealer (who shall remain unnamed as they are noteworthy) had zero interest in making sure I had a good solution for me, just moving a unit.  There are other dealers who are great and I have vowed not to be that guy in my own business, but it is quite frustrating when it happens.    

Fortunately, I found The Music Room and I was able to execute a trade for a DAC and the whole thing only cost me $500 rather than $2500 which is the loss I would have taken selling them.  

My biggest and most costly mistake was selling a Krell KPS20i cd player, that I owned and loved for many years. But after 20 years I assumed digital should have advanced enough to merit an upgrade. In the last 5 years various supposedly more 'advanced' cd players from brands like Metronome and Esoteric came and went. None of them delivered the sonic improvements I had expected.  

So after about $7500 worth of buying and reselling different players I finally accepted my mistake and decided to simply buy back the 20i. Back to the future. As chance would have it, the 'new' one is only one serial number removed from the one I previously had.......

It goes to show that technological progress, which is undeniable in digital, does not necessarily result in better sound. In fact the same applies to the discs themselves: most higher bit remasters don't sound any better than the first cd issues. 

edgewear

Thanks,
sorry for your lost,
but very informative for us all.....