Can you please help me find some speakers with knob volume controls?

go to any office supply sotre, like staples or london drugs or whatever you have, most desktop computer speakers have them.

That’s the same pre-amp as in your other question.
It does not look like it has an output that’s usable for speakers.
There isn’t much information on the URL but it looks like the only output is over USB, you’ll have to hook that pre-amp into your computer and use the computer speakers.

I agree with @dabbler. Speakers are normally driven by an amplifier, not a pre-amplifier.

Amplifiers output an electrical signal, at a low impedance to match the speakers, with enough voltage & current to generate sound waves from the speakers. The output of a preamp, by contrast, has a lower “line level” voltage & higher impedance—inadequate to drive all but the tiniest & tinniest speakers, but ideal for either recording or amplifier input.

Preamps condition or process the raw signal by various analog and digital means, including (in this case) digitally encoding a usb signal. No more analog,

@_Whitetigress, try to find usb-powered amplified speakers. You can squeeze a few watts from a usb port, while low-powered audio amps can be made small & cheap & you only need one cable. I see that your gadget has line-level audio outputs as well as usb, so you could go the conventional route of amp & big speakers. The “gain” knob should function as a master volume control in any case.