adaptor studs for speaker spikes needed

I recently bought a couple of amp stands that came with these really cheesy cheap spikes. The stands are threaded for a 5/16-18 and the spikes I have and want to use are threaded 1/4-20. Any ideas as to where I kind find some adaptors that have male 1/4-20 threads to a 5/16-18 male threads??? I know that I can tap the spikes out to a 5/16-18, but that is my last resort. I know that Polycrystal sells the adaptors that I am looking for, but Polycrystal wants an arm and a leg for anything and everything. I've already checked the web sites for MCM Electronics and Parts Express with no luck there. Any info would be a great help. Thank you.
There is a product called Helicoil that is designed to repair stripped threads. Below is a link to their web site. It's possible the conversion exists as a normal repair part, in which case it would be cheap.
Star Sound's Audio Points are deemed by some to be the very best points available and their prices are very reasonable compared to many other brands.

I use them under all components, racking system, and speakers and the sonic improvements were nothing short of amazing after the mechanical break-in period.

I know it's easy to do, but one should never assume that all points/spikes are created equally.

Anyway, if they do not stock your specific threading, perhaps they may be able make them for you. is their web-site address.

Polycrystal makes a line of studs for spikes in many different sizes and threads.
I've purchased the type of adaptor you need at camera stores for my tripod to fit different heads. A package of two runs about $3. I found this source online for various adaptors.