Help with the LM1875 amplifier chip??

 do i need a 4A supply, or is that just the most it can handle? ie can i use a 18V 1.4A transformer with it? i realize it wont be working the chip's potential, but that's not a big deal to me i just want it to work.

No problem, it just won't deliver 20W into the stated load, that's all.
It'll be loud enough though....
Steve
Seconded.  Wattages are usually maximum ratings - you can use any or all of it, but it wont put out more.