amps like this are usually connected to a computer by an RCA to headphones jack cable

you can use any class D amp. the manufacturer “S. M. S. L” is recommended for good quality amps, but any will do.

Answered above already. Anyway, you can use any Class-D / Class-T amp.

This will most likely not work, as the USB Subwoofer has to be supported by your operating system. As far as I remember Apple stopped support for those USB subwoofers a long time ago and in addition to that they were only supported on few computers (like the second generation iMacs). Even if it would work, you'd have two separate volumes – one for the subwoofer and one on the Pro Speakers amp. It's a pity. Long ago I had an iMac "snow" in combination with this USB iSub and it sounded terrfic. What you could do is to disassemble the sub and connect the speaker directly with the amp where you also hook up the Pro Speakers, but this requires a little bit more technical insight and I would not recommend to do it.

Sure, you can just connect the speakers directly!

Great to hear that :] It's a good thing to see some Pro Speakers getting revived!

Should work. Not the 'best' amp out there, but same tripath chip as most other class-d amps on the market.

Thanks chuck, I have corrected the wire covering term :)