He'll need either an "MC" setting/switch or a step-up transformer going into a receiver (most of which are based around the premise of using a MM cartridge where the output voltage is 10-12 greater than a typical MC). In other words, a typical MM has an output of around 3.0-5.0 mV, compared to an MC which has an output of only around .25mV. Big difference - if you try to simply plug it into a circuit for MM cartridges, you'll get a lot of noise and not much fidelity.
I would speculate that if he's using a receiver, he most likely doesn't have a turntable that's up to handling a 103. As most folks start out in analog, they'll try a 103 and typically be rather underwhelmed - the logic being it's affordable and well-respected (both of which are true, just not for the novice or casual analog dabbler). You really need a table and especially an arm that is up to the task. Look at what turntables and tonearms are being used by folks who rave about how good the 103 is for so little money - none of them would be considered modest.
The usual disclaimers apply.
