Yeah, I understand very well. My disability is different, but money is still tight and when my Sound Blaster died it was really annoying trying to find a way to replace it within my budget and without rearranging my whole setup. I'm new to audiophile stuff too so it's intimidating and a lot to learn.

For my use case, I look more into the USB audio interface side of things because I need to have an XLR input and a monitoring plug with zero latency. If you don't need anything like that, then a DAC or a DAC/amp combo is what you want. I'm not really an audiophile and this is getting into that area so I'm not the best person to explain it. Definitely take anything I say with a grain of salt and make sure you check. But I think you only really need the amp if it's required to drive your headphones. If you don't have high impedance headphones, then you should be able to skip the amp and just get any DAC that fits your needs.

There's a huge variety of brands, price points, and features. It's dipping your toe into the audiophile world so the rabbit hole is bottomless, but you can also find very good quality gear on a budget. FiiO, Topping, and Hifiman are brands I recognize, but there are plenty of others I don't which I'm sure would still be good. It's the kind of gear somebody buys and expects to still be working in ten years.

The one thing I personally would look for is I would avoid anything with an internal battery. That's why my Sound Blaster died. For whatever reason, they gave it an internal battery so you could unplug it and use it as a portable headphone amp. I never needed or wanted that, but the battery started expanding and died after over ten years, so that was the end. It's not a feature I care about, so I'm better off getting something without a battery.

For what it's worth, a quick search suggests any USB DAC should work fine in both Windows and Linux as long as it doesn't require special software. So if you look for an affordable USB DAC with physical buttons/dials and all the inputs and features you want, that should help narrow things down to start. You can definitely find one with multiple inputs for both the speakers and a headset, and possibly different volume settings. But I'm not sure - different settings for different inputs might also be more in the realm of a USB audio interface, which may not be as good of a fit for your situation. But you could always look: Focusrite Scarlett 2i2 and Motu M2 2x2 are very strong contenders for me.

Also, at least in the US, Sweetwater is a reputable site for audio gear. I'm sure there are others, of course, but it's a start.

Good luck!