Help connecting a source directly to an amp

A month or so back, I posted a question for a friend who had just picked up some massive, DIY speakers. They were free, and this is his motif: get sound, enough to enjoy and dance to, for as little money as possible. (Let's agree he's a budding audiophile.) He now has picked up an amplifier, also free. I think it's an amp for DJing, although I think that his friend also used it to plug in a guitar and wail. 

He's hoping to connect his source (an iPhone or laptop) to the amp without the nuisance and expense of a pre-amp. The inputs on the back of the amp are balanced/XLR and ... what looks to me like a pair of 1/4" TRS jacks. As you can tell, I've never done this and simply don't know the basic electronics. 
So: is there a way to connect an iPhone directly to either XLR inputs or (what looks like) 1/4" inputs? 

Here's a picture of the inputs on the back of the amp:

And just because it's such a fun picture, here are the speakers that he picked up:

I know this isn't exactly a high-end audiophile question but I hope y'all appreciate the spirit of my friend's quest for music! He and I are ready to be schooled. Thanks!
Theoretically,  you need a stereo jack to XLR like this.
However, if your iPhone has no 2.5mm jack and only a Lightning jack, you'll need some sort of converter. 
Pro sound equipment usually has only balanced and 1/4 inch connections.  The usually are not that friendly for home audio.  
@noromance, YES! I was wondering if a cable adapter like that existed. I'll go with "theoretically." 

@stereo5, yes--he knows that. But when you say "not that friendly," do you mean incompatible? Or just ... not ideal for producing an inviting sound?
You can get an analog output from a phone through apple connectors... I assume an old phone so simple, the 1/8” inch socket on the bottom. The connectors on the amp must be RCA... unless it is something really out in left field. You can get 1/8” output to two RCA connectors. BUT, he needs to be really careful or it’s going to send full amp power to the speakers when futzing with the iPhone. It is a disaster waiting to happen... but if he is really careful it may work... but the iPhone has an amplifier and may be capable of output greater than line level... some one with a technology bent here can probably talk about that.


If the amp really has 1/8” inputs I am sure you can find the right adapters on Amazon.
Every iPhone since the iPhone 5 introduced in 2012 has a Lightning connector rather than a 3.5mm stereo connector. If it does have the Lightning connector there is an Apple adapter that would allow you to use the 1/8" to XLR cable that noromance suggested.