I agree with ghasley that this is a nothingburger. Here' why. The following assumes that you buy and sell gear as a hobby and that you do not have a business buying and selling things like amps and DACs.
For 99% of the gear you sell you will take a loss. When you report your taxes you will fill out your form and show that you took a loss on the items you sold. Therefore, no taxes due. If you sold 10 pieces of gear and took a loss on 9 of them you can use the total loss amount to offset the gain you made on one piece. No tax due again.
You do not need the receipt. This is because you do not send copies of your receipts when you file your taxes. The only time you might possibly need a receipt is if you get a TCMP audit (Taxpayer Compliance Measurement Program) where an IRS agent will go through your return line by line. This is very rare but if it happens you can show the agent that the retail price of the item is higher than the price you sold it for.. Any documentation will do - i.e. magazine review, internet review, audio buyer's guide, etc. If you bought it used you can probably locate a record of the transaction (email confirmation for example) to show that you sold it for less than you bought it for. Even if you have no records there's a miniscule chance that the agent will sweat you about it. They've got much bigger fish to fry. Just treat them with respect and don't piss them off.
I've had a TCMP audit and it's no fun but I can tell you that the agent is way too busy to be concerned about a few pieces of audio gear. They also operate by using common sense. Everybody knows that audio gear depreciates over time and trying to charge you income tax on something that obviously depreciated would never stand up if you contest the audit..
In other words, relax. When you file your 1040 for 2022 and you have a few 1099s for audio gear, just show that you sold each item at a loss. It's really that simple. Nobody will pay taxes on hobby items that they bought and subsequently sold at a loss.
Have a beer. Listen to some Trip Hop. It's going to be OK.