I'm looking for inexpensive bookshelf speakers that are compatible with the sonic impact amp.
FYI: Unfortunately, I'm not a DIYer.
OK, but can use use a knife or razorblade? The cheapest, best sounding speaker wire for the Sonic Impact for low-power application I've found is the 20 AWG Vampire continuous cast solid core copper wire. This is the so-called magnet wire and is coated with enamel.
And it's extremely cheap. Look at Michael Percy's catalogue. All you gotta do is buy enough for your needs, cut it to length you need, and strip the ends with knife. Sonic Impact only can accept thin bare wire ends anyway.
If you are up to it, I would use 2 of the 20 AWG per each leg(just loosely twisted). So if you need 6 foot long speaker cable, it's 6 ft x8=48 foot you need. It's technically DIY there's no soldering, no jacketing, no nothing.