What has been your costliest mistake in this hobby?


For example :I recently learned a hard lesson- I accidentally ran voltage thru my $3000 MC cartridge (kiseki purple heart).  I have a TT with 5 prong connector and a phono cable with a 5 prong connector.  I accidentally swapped where they plugged into and ran electric thru the tonearm into the cartridge.  It was a stupid - not thinking- hasty mistake. When I corrected the problem the cartridge was fried.  An avalanche of four letter words followed!

So what has been your biggest and/or costliest mistake?
polkalover
Also blew out one channel of a nice Yamaha Receiver in the 80's.....disconnected the speaker to paint, the wires shorted and the unit was on.  Learned that lesson....
Maybe spending inordinate amounts of time on line trying to decipher what will catapult my system into nirvana. 
Champagne tastes on a beer budget is difficult. 
Democracy (read as spouse) can be a limiting factor. 
Maybe spending inordinate amounts of time on line trying to decipher what will catapult my system into nirvana.
Champagne tastes on a beer budget is difficult.
Democracy (read as spouse) can be a limiting factor.
Dont be discouraged.... All is possible, i made it, champagne taste on a glass of water soda budget.... :)
Maybe spending inordinate amounts of time on line trying to decipher what will catapult my system into nirvana.
Champagne tastes on a beer budget is difficult.
Democracy (read as spouse) can be a limiting factor.
Dont be discouraged my friend...

All is possible , champagne taste with a glass of soda budget, i made it for myself, it only need creativity and time, Dont be discouraged and read and think....

I wish you the best....
35 years and lots of mistakes.

1) Selling good gear for more expensive gear that was no better in the end or worse.  
2)Trusting dealers opinions. 
3) Buying unproven designs that sound great then break down... 
4) (Just recently) buying from 2 designers that went bankrupt (or died, Roy Johnson Green Mountain Audio) while they have my money and gear under repair or upgrade and I never get it back. This alone has cost me 20K. Several other members here got the same treatment.