[Cruelhand Luke]

here are the Senitek pads. They come in cloth, suede and pleather I think. I have the cloth....they jumped up in price. I paid $12.00 a few months ago. I think they are still a good price at less than $20.00. For comparison I have these, Brainwavz Hybrids, NVX Flats and angled , Fidelio L2 pleather ...the Senitek are pretty close in quality. Not quite as good, but close enough (especially for the Monoprice headphones...I had them on mine, they fit good...a little loose if I remember, but nothing I'd call a problem. They are about $10 less than HM5 pads...and about the same as NVX pads (which are identical to HM5 pads but super plush and comfy)
https://www.amazon.com/dp/B071X2K9YQ/ref=twister_B0714GB6BK?_encoding=UTF8&psc=1

 

[Cruelhand Luke]

Are those the stock pads underneath the socks? I'm curious about which $12.00 Senitek pads would be compatible with the 8323 / 24735.

yeah, stock pads with BRAND NEW socks wrapped over them...that was an acceptable configuration. It's much easier (and they fit and sound better) to just buy new pads.
My favorite pads for the Monoprice were actually the Fidelio L2 pads, but it seems like the only way to get those is to buy a set of L2s or, of course, fatally vanquish an L2 owner with a sword (pronounced with a W) and become the rightful owner of their L2 pads, because nobody is selling them.