Audio tax write-off

You don't set a dollar threshold.  Whether it cost $1,000 or $20,000, it is still subject to the rules of depreciation and is not an expendable asset.  You may be confusing an expendable asset with a section 179 deduction.

You’re right as far as you go. Define capital assets? It’s life expectancy and cost there has to be a cost threshold or like I said we would be depreciating staplers and ink pens.

An auditor would turn his or her head if you expensed a stapler, because it most likely would be deductible as a 179 deduction anyway.  A $5,000 dollar computer.  No.  This is basic stuff.

IRS publication 946, page 3:

You can depreciate most types of tangible property (except land), such as buildings, machinery, vehicles, furniture, and equipment. You can also depreciate certain intangible property, such as patents, copyrights, and computer software. To be depreciable, the property must meet all the following requirements. • It must be property you own. • It must be used in your business or income-producing activity. • It must have a determinable useful life. • It must be expected to last more than 1 year. The following discussions provide information about these requirements.

The section 179 discussion  begins on page 15.  If after reading that, you have further questions, don't hesitate to ask.

Wow, thank you for all of this input. I assumed that my situation was fairly unique, and therefore I plan to consult my accountant about the tax details. It's an LLC with just yours truly as its owner and employee. I have a dedicated home office space that also happens to contain my stereo.  I say "happens" because I use all the sound absorption paneling when recording narration and conducting some of my interviews. It also contains my A/V editing system, which currently has headphones or laptop speakers as the audio out, and I am considering acquiring monitors for that purpose and perhaps an outboard DAC. The consensus seems to be that to write such off is fine so long as you are using the equipment for stated purpose and my home office setup gibes with the tax rules for my particular corporation. I have friends in Canada who write off their stereo systems because they run a record label. A reference system, multiple systems in fact, are a totally legitimate expense there. For my part, sound quality and balance is absolutely a feature of my products, so I would be making that case. Just curious if others had done the same. To be clear, I am not trying to cheat. But I would feel ridiculous if I had to shift my whole stereo out of that room because it might be perceived by an auditor as not being a home office, especially when my work is A/V recording and editing. 

Yes talk to your tax guy or gal it looks like it's a business expense.